Dimeric Alpha Interferon PEGylated Site-Specifically Shows Enhanced and Prolonged Efficacy in Vivo

ABSTRACT

The present invention concerns methods and compositions for PEGylated complexes of defined stoichiometry and structure. Preferably, the PEGylated complex is formed using dock-and-lock technology, by attaching a therapeutic agent to a DDD sequence and a PEG moiety to an AD sequence, allowing the DDD sequence to bind to the AD sequence in a 2:1 stoichiometry, to form PEGylated complexes with two therapeutic agents and one PEG moiety. Alternatively, the therapeutic agent may be attached to the AD sequence and the PEG to the DDD sequence to form PEGylated complexes with two PEG moieties and one therapeutic agent. In more preferred embodiments, the therapeutic agent may comprise any peptide or protein of physiologic or therapeutic activity, preferably a cytokine, more preferably interferon-α2b. The PEGylated complexes exhibit a significantly slower rate of clearance when injected into a subject and are of use for treatment of a wide variety of diseases.

RELATED APPLICATIONS

The present application is a divisional of U.S. Ser. No. 13/412,816, filed Mar. 6, 2012, which was a divisional of U.S. Ser. No. 13/178,092 (now issued U.S. Pat. No. 8,158,129), filed Jul. 7, 2011, which was a continuation-in-part of U.S. Ser. No. 12/731,781 (now issued U.S. Pat. No. 8,003,111), filed Mar. 25, 2010, which was a continuation-in-part of U.S. Ser. No. 12/396,965 (now issued U.S. Pat. No. 7,871,622), filed Mar. 3, 2009, which was a divisional of U.S. Ser. No. 11/391,584 (now issued U.S. Pat. No. 7,521,056), filed Mar. 28, 2006, which claimed the benefit of U.S. Provisional Patent Applications 60/668,603, filed Apr. 6, 2005; 60/728,292, filed Oct. 19, 2005; 60/751,196, filed Dec. 16, 2005; and 60/782,332, filed Mar. 14, 2006. U.S. Ser. No. 12/731,781 was a continuation-in-part of U.S. Ser. No. 12/417,917 (now issued U.S. Pat. No. 7,906,121), filed Apr. 3, 2009, which was a divisional of U.S. Ser. No. 11/478,021 (now issued U.S. Pat. No. 7,534,866), filed Jun. 29, 2006.

U.S. Ser. No. 12/731,781 was also a continuation-in-part of U.S. Ser. No. 12/396,605 (now issued U.S. Pat. No. 7,858,070), filed Mar. 3, 2009, which was a divisional of U.S. Ser. No. 11/633,729 (now issued U.S. Pat. No. 7,527,787), filed Dec. 5, 2006, which was a continuation-in-part of PCT/US06/010762, filed Mar. 24, 2006, PCT/US06/012084, filed Mar. 29, 2006, PCT/US06/025499, filed Jun. 29, 2006, U.S. Ser. No. 11/389,358 (now issued U.S. Pat. No. 7,550,143), filed Mar. 24, 2006, and claimed the benefit of U.S. Provisional Patent Application 60/864,530, filed Nov. 6, 2006.

U.S. Ser. No. 12/731,781 was also a continuation-in-part of U.S. Ser. No. 12/418,877 (now issued U.S. Pat. No. 7,906,118), filed Apr. 6, 2009, which claimed the benefit of U.S. Provisional Patent Applications 61/043,932, filed Apr. 10, 2008, 61/104,916, filed Oct. 13, 2008, and 61/119,542, filed Dec. 3, 2008. U.S. Ser. No. 12/731,781 was also a continuation-in-part of U.S. Ser. No. 12/644,146 (now issued U.S. Pat. No. 7,981,398), filed Dec. 22, 2009, which was a divisional of U.S. Ser. No. 11/925,408 (now issued U.S. Pat. No. 7,666,400), filed Oct. 26, 2007. U.S. Ser. No. 12/731,781 claimed the benefit under 35 U.S.C. 119(e) of U.S. Provisional Patent Application 61/163,666, filed Mar. 26, 2009. The text of each priority application cited above is incorporated herein by reference in its entirety.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has been submitted via EFS-Web and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Mar. 24, 2010, is named IBC123US.txt and is 14,095 bytes in size.

BACKGROUND

1. Field of the Invention

The present invention relates to compositions and methods of therapeutic use of PEGylated cytokines, such as interferon-alpha (IFN-α), more preferably IFN-α2b. However, the skilled artisan will realize that the invention is not so limited and more broadly covers PEGylated forms of other immunomodulators or different therapeutic agents. Preferably, the PEGylated compositions are made using the dock-and-lock (DNL) technique, as exemplified in U.S. Pat. Nos. 7,521,056; 7,527,787; 7,534,866; 7,550,143 and 7,666,400, the Examples section of each of which is incorporated herein by reference. The PEGylated cytokines, immunomodulators and other therapeutic agents retain in vitro activity and preferably show enhanced in vivo efficacy and increased serum half-life. Additional advantages of the PEGylated products may also include lower immunogenicity, decreased dosing frequency, increased solubility, enhanced stability, and reduced renal clearance.

2. Related Art

Interferon

Interferon-α (IFNα) has been reported to have anti-tumor activity in both animal models of cancer (Ferrantini et al., 1994, J Immunol 153:4604-15) and human cancer patients (Gutterman et al., 1980, Ann Intern Med 93:399-406). IFNα can exert a variety of direct anti-tumor effects, including down-regulation of oncogenes, up-regulation of tumor suppressors, enhancement of immune recognition via increased expression of tumor surface MHC class I proteins, potentiation of apoptosis, and sensitization to chemotherapeutic agents (Gutterman et al., 1994, PNAS USA 91:1198-205; Matarrese et al., 2002, Am J Pathol 160:1507-20; Mecchia et al., 2000, Gene Ther 7:167-79; Sabaawy et al., 1999, Int J Oncol 14:1143-51; Takaoka et al, 2003, Nature 424:516-23). For some tumors, IFNα can have a direct and potent anti-proliferative effect through activation of STAT1 (Grimley et al., 1998 Blood 91:3017-27).

Indirectly, IFNα can inhibit angiogenesis (Sidky and Borden, 1987, Cancer Res 47:5155-61) and stimulate host immune cells, which may be vital to the overall antitumor response but has been largely under-appreciated (Belardelli et al., 1996, Immunol Today 17:369-72). IFNα has a pleiotropic influence on immune responses through effects on myeloid cells (Raefsky et al, 1985, J Immunol 135:2507-12; Luft et al, 1998, J Immunol 161:1947-53), T-cells (Carrero et al, 2006, J Exp Med 203:933-40; Pilling et al., 1999, Eur J Immunol 29:1041-50), and B-cells (Le et al, 2001, Immunity 14:461-70). As an important modulator of the innate immune system, IFNα induces the rapid differentiation and activation of dendritic cells (Belardelli et al, 2004, Cancer Res 64:6827-30; Paquette et al., 1998, J Leukoc Biol 64:358-67; Santini et al., 2000, J Exp med 191:1777-88) and enhances the cytotoxicity, migration, cytokine production and antibody-dependent cellular cytotoxicity (ADCC) of NK cells (Biron et al., 1999, Annu Rev Immunol 17:189-220; Brunda et al. 1984, Cancer Res 44:597-601).

The therapeutic effectiveness of IFNs has been validated to date by the approval of IFN-α2 for treating hairy cell leukemia, chronic myelogenous leukemia, malignant melanoma, follicular lymphoma, condylomata acuminata, AIDs-related Kaposi sarcoma, and chronic hepatitis B and C; IFN-β for treating multiple sclerosis; and IFN-γ for treating chronic granulomatous disease and malignant osteopetrosis. Despite a vast literature on this group of autocrine and paracrine cytokines, their functions in health and disease are still being elucidated, including more effective and novel forms being introduced clinically (Pestka, 2007, J. Biol. Chem. 282:20047-51; Vilcek, 2006, Immunity 25:343-48).

Therapy of viral infection with IFNs has been reported for a wide variety of viral species. The combination of IFN-α and IFN-γ or IFN-β and IFN-γ was reported to inhibit replication of dengue virus (Diamond & Harris, 2001, Virology 289:297-311). Low dose prophylactic oral administration of IFN-α protected against a lethal challenge with influenza virus (Belharz et al., 2007, Biochem Biophys Res Commun 355:740-44). Similarly, prophylactic IFN-α-2 reduced rhinovirus-induced infection (Morey & Blackwell, 1989, Aviat Space Environ Med 60:1028). The combination of IFN-α-6 and IFN-β was reported to synergistically reduce infection with cytomegalovirus when administered prophylactically. A synergistic effect of IFN-β and IFN-γ was also reported for reducing acyclovir-resistant herpes simplex viral infection (Huang et al., 2010, J Gen Virol 91:591-98). IFN-γ was observed to inhibit DNA synthesis of vaccinia virus in macrophages (Melkova & Esteban, 1994, Virology 198:731-35). An IFN-γ mimetic peptide prevented encephalomyocarditis virus infection in both tissue culture and in vivo in mice (Mujtaba et al., 2006, Clin Vaccine Immunol 13:944-52).

The promise of IFNα as a cancer therapeutic has been hindered primarily due to its short circulating half-life and systemic toxicity. As demonstrated by PEGINTRON® (Grace et al., 2001, J. Interferon Cytokine Res 21:1103-15) and PEGASYS® (Bailon et al., 2001, Bioconjugate Chem 12:195-202), the efficacy of IFNs can be enhanced by improving their bioavailability with PEGylation, with the resulting conjugate exhibiting an increased serum half-life (Harris and Chess, 2003, Nat Rev Drug Discov 2:214-21). Additional advantages of PEGylation in general include reduced immunogenicity, decreased dosing frequency, increased solubility, enhanced resistance to proteolysis, and exclusion of renal clearance.

PEGylation

Because the most common reactive sites on proteins (including peptides) for attaching PEG are the ε amino groups of lysine and the α amino group of the N-terminal residue, early methods of PEGylation resulted in modification of multiple sites, yielding not only monoPEGylated conjugates consisting of mixtures of positional isomers, such as PEGINTRON®™ (Grace et al., J. Biol. Chem. 2005; 280:6327) and PEGASYS®® (Dhalluin et al., Bioconjugate Chem. 2005; 16:504), but also adducts comprising more than one PEG chain. Site-specific attachment of a single PEG to the a amino group of the N-terminal residue was reported to be the predominant product upon reacting PEG-aldehyde (PEG-ALD) at low pH with IFN-β1b (Basu et al., Bioconjugate Chem. 2006; 17:618) or IFN-β1a (Pepinsky et al., J. Pharmacol. Exp. Ther. 2001, 297:1059). Similar strategies were applied to prepare N-terminally linked PEG to G-CSF (Kinstler et al., Pharm. Res. 1996; 13:996) or type I soluble tumor necrosis factor receptor (Kerwin et al., Protein Sci. 2002; 11:1825). More recently, a solid-phase process for PEGylation of the N-terminus of recombinant interferon alpha-2a was reported (Lee et al., Bioconjug. Chem. Oct. 18, 2007, epub).

Site-directed PEGylation of a free cysteine residue introduced into a target protein has also been achieved with PEG-maleimide (PEG-MAL) for several recombinant constructs including IL-2 (Goodson and Katre, Biotechnology. 1990:8:343); IFN-α2 (Rosendahl et al., Bioconjugate Chem. 2005; 16:200); GM-CSF (Doherty et al., Bioconjugate Chem. 2005; 16:1291); scFv (Yang et al., Protein Eng. 2003; 16:761), and miniantibodies (Kubetzko et al., J. Biol. Chem.; 2006; 201:35186). A popular approach for improving the therapeutic efficacy of an enzyme has been to prepare conjugates containing multiple PEG of small size, as known for methioninase (Yang et al., Cancer Res. 2004; 64:6673); L-methionine γ-lyase (Takakura et al., Cancer Res. 2006:66:2807): arginine deaminase (Wang et al., Bioconjugate Chem. 2006; 17:1447); adenosine deaminase (Davis et al., Clin. Exp. Immunol. 1981, 46:649); L-asparaginase (Bendich et al., Clin. Exp. Immunol. 1982, 48:273); and liver catalase (Abuchowski et al., J. Biol. Chem. 1977, 252:3582).

PEGylations of bovine serum albumin (Abuchowski et al., J. Biol. Chem. 1977; 252:3578); hemoglobin (Manjula et al., Bioconjugate Chem. 2003; 14:464); visomant (Mosharraf et al., Int. J. Pharm. 2007; 336:215); small molecules such as inhibitors of integrin α4β1 (Pepinsky et al., J. Pharmacol. Exp. Ther. 2005, 312:742); lymphoma-targeting peptides (DeNardo et al., Clin. Cancer. Res. 2003; 9(Suppl.):3854s); anti-VEGF aptamer (Bunka and Stockley, Nat. Rev. Microbiol. 2006; 4:588) and oligodeoxynucleotides (Fisher et al., Drug Metab. Dispos. 2004; 32:983) have also been described. The feasibility of reversible or releasable PEGylation, wherein covalently attached PEG can be cleaved in vivo, has been shown with a variety of degradable linkages, exemplified by linking PEG-SH to IFN-α2 with a 2-sulfo-9-fluorenylmethoxycarbonyl-containing bifunctional reagent (Peleg-Shulman et al., 2004, J Med Chem 47:4897-4904), by attaching linear or branched PEG-BCN3 to lysozyme or IFN-β1b (Zhao et al., 2006, Bioconjugate Chem 17:341-51), or by conjugating PEG to lysozyme via a dithiobenzyl urethane linkage (Zalipsky et al., 2007, Bioconjugate Chem 18:1869-78). Recently, a strategy for site-specific PEGylation of disulfide bonds has been reported (Shaunak et al., 2006, Nat Chem Biol 2:312-13), but its use may be limited to only those proteins with native disulfide bonds that are suitably oriented for such modification.

There exists a need for a general method of PEGylation that would produce a monoPEGylated or a biPEGylated conjugate linked site-specifically to a predetermined location of a therapeutic agent such as a cytokine, which retains the bioactivity of the unmodified agent. A further need exists for PEG-cytokine conjugates that exhibit improved in vivo efficacy, decreased toxicity and/or superior pharmacokinetic properties.

SUMMARY OF THE INVENTION

The present invention discloses methods and compositions for producing PEGylated compounds that can be selected to contain either one or two PEG residues, attached at a selected location of a therapeutic agent, such as a cytokine, preferably IFN-α2b. The PEGylated cytokines are prepared using the Dock-and-Lock method (Chang et al., 2007, Clin Cancer Res 13:5586s-91s), which generates stable and defined conjugates suitable for in vivo applications.

In preferred embodiments, the agents are monoPEGylated. In more preferred embodiments, the agent to be PEGylated may be attached to a DDD (dimerization and docking domain) sequence and a PEG moiety may be attached to an AD (anchor domain) sequence as described in more detail below. Dimers of the DDD sequence bind with high affinity to monomers of the AD sequence, resulting in formation of a monoPEGylated therapeutic agent dimer. The stoichiometry of binding and location of the PEG residue are determined by the specificity of the DDD/AD interaction, with a preferred trimeric structure comprising two DDD moieties attached to one AD moiety. However, the skilled artisan will realize that other types of DNL complexes with different structures and different ratios of cytokine to PEG may be constructed and used within the scope of the claimed methods and compositions, such as those disclosed in U.S. Pat. Nos. 7,521,056; 7,527,787; 7,534,866; 7,550,143 and 7,666,400.

In more preferred embodiments, the monoPEGylated complex may be covalently stabilized by introduction of cysteine residues at appropriate locations in the DDD and AD sequences, to form disulfide bonds that stabilize the complex. In other embodiments, the PEG reagents may be capped at one end with a linear or branched methoxy group (m-PEG). Either linear PEG or branched PEG molecules, as known in the art, may be utilized.

In other preferred embodiments, the PEGylated complex made by the DNL method shows a rate of clearance from serum that is at least an order of magnitude slower than the unPEGylated therapeutic agent. In certain alternative embodiments, the PEGylated complex may be alternatively constructed with the PEG moiety attached to the DDD sequence and the therapeutic agent attached to the AD sequence, resulting in a stoichiometry of 2 PEG to 1 therapeutic agent, such as a cytokine, per complex.

The skilled artisan will realize that virtually any physiologically or therapeutically active agent to be administered in vivo may be stabilized by PEGylation, including but not limited to enzymes, cytokines, chemokines, growth factors, peptides, aptamers, hemoglobin, antibodies and fragments thereof. Exemplary agents include MIF, HMGB-1 (high mobility group box protein 1), TNF-α, IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-13, IL-15, IL-16, IL-17, IL-18, IL-19, IL-21, IL-23, IL-24, CCL19, CCL21, IL-8, MCP-1, RANTES, MIP-1A, MIP-1B, ENA-78, MCP-1, IP-10, Gro-β, Eotaxin, interferon-α, -β, -λ, G-CSF, GM-CSF, SCF, PDGF, MSF, Flt-3 ligand, erythropoietin, thrombopoietin, hGH, CNTF, leptin, oncostatin M, VEGF, EGF, FGF, PlGF, insulin, hGH, calcitonin, Factor VIII, IGF, somatostatin, tissue plasminogen activator, and LIF.

The PEGylated complexes are suitable for use in a wide variety of therapeutic and diagnostic applications. Methods of use of PEGylated DNL complexes may include detection, diagnosis and/or treatment of a disease or other medical condition. Such conditions may include, but are not limited to, cancer, hyperplasia, diabetes, diabetic retinopathy, macular degeneration, inflammatory bowel disease, Crohn's disease, ulcerative colitis, rheumatoid arthritis, sarcoidosis, asthma, edema, pulmonary hypertension, psoriasis, corneal graft rejection, neovascular glaucoma, Osler-Webber Syndrome, myocardial angiogenesis, plaque neovascularization, restenosis, neointima formation after vascular trauma, telangiectasia, hemophiliac joints, angiofibroma, fibrosis associated with chronic inflammation, lung fibrosis, deep venous thrombosis or wound granulation.

In particular embodiments, the disclosed methods and compositions may be of use to treat autoimmune disease, such as acute idiopathic thrombocytopenic purpura, chronic idiopathic thrombocytopenic purpura, dermatomyositis, Sydenham's chorea, myasthenia gravis, systemic lupus erythematosus, lupus nephritis, rheumatic fever, polyglandular syndromes, bullous pemphigoid, juvenile diabetes mellitus, Henoch-Schonlein purpura, post-streptococcal nephritis, erythema nodosum, Takayasu's arteritis, Addison's disease, rheumatoid arthritis, multiple sclerosis, sarcoidosis, ulcerative colitis, erythema multiforme, IgA nephropathy, polyarteritis nodosa, ankylosing spondylitis, Goodpasture's syndrome, thromboangitis obliterans, Sjogren's syndrome, primary biliary cirrhosis, Hashimoto's thyroiditis, thyrotoxicosis, scleroderma, chronic active hepatitis, polymyositis/dermatomyositis, polychondritis, pemphigus vulgaris, Wegener's granulomatosis, membranous nephropathy, amyotrophic lateral sclerosis, tabes dorsalis, giant cell arteritis/polymyalgia, pernicious anemia, rapidly progressive glomerulonephritis, psoriasis or fibrosing alveolitis.

Exemplary types of tumors that may be treated include acute lymphoblastic leukemia, acute myelogenous leukemia, biliary cancer, breast cancer, cervical cancer, chronic lymphocytic leukemia, chronic myelogenous leukemia, colorectal cancer, endometrial cancer, esophageal, gastric, head and neck cancer, Hodgkin's lymphoma, lung cancer, medullary thyroid cancer, non-Hodgkin's lymphoma, multiple myeloma, renal cancer, ovarian cancer, pancreatic cancer, glioma, melanoma, liver cancer, prostate cancer, and urinary bladder cancer.

Various viral infections may be treated, including but not limited to human immunodeficiency virus (HIV), herpes virus, herpes simplex virus, vaccinia virus, cytomegalovirus, rabies virus, influenza virus, rhinovirus, hepatitis B virus, hepatitis C virus, Sendai virus, feline leukemia virus, Reo virus, polio virus, human serum parvo-like virus, simian virus 40, respiratory syncytial virus, mouse mammary tumor virus, Varicella-Zoster virus, Dengue virus, rubella virus, measles virus, adenovirus, human T-cell leukemia viruses, Epstein-Barr virus, murine leukemia virus, mumps virus, vesicular stomatitis virus, Sindbis virus, lymphocytic choriomeningitis virus, wart virus and blue tongue virus; or the bacterium is selected from the group consisting of Streptococcus agalactiae, Legionella pneumophila, Streptococcus pyogenes, Escherichia coli, Neisseria gonorrhoeae, Neisseria meningitidis, Pneumococcus, Hemophilus influenzae B, Treponema pallidum, Lyme disease spirochetes, Pseudomonas aeruginosa, Mycobacterium leprae, Brucella abortus, Mycobacterium tuberculosis or Clostridium tetani.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Schematic structures of (A) IMP421, (FIG. 1A discloses SEQ ID NO: 22) (B) IFNα2b-DDD2-pdHL2 (FIG. 1B discloses SEQ ID NO: 31 and 6H is disclosed as SEQ ID NO: 30).

FIG. 2. Reducing (R) and nonreducing (NR) SDS-PAGE analysis of the conjugation and purification of α2b-362 and α2b-413. Gels were stained with Coomassie blue (A and D), imaged with direct fluorescence (B and E) or transferred to PVDF membranes and probed by immunoblotting with anti-IFN-α (C). Arrowheads show the positions of α2b-362 (black), α2b-413 (gray), IFNα2b-DDD2 (red), IMP362 (green) and IMP413 (blue). Lane 1, IFNα2b-DDD2; Lane 2, the reaction mixture of α2b-362 before purification; Lane 3, unbound fraction of α2b-362; Lane 4, wash fraction of α2b-362 (0.25 M NaCl elution); Lane 5, purified α2b-362 (0.5 M NaCl elution); Lane 6, purified 2b-413; Lane M, pre-stained molecular weight markers; Lane E, ECL molecular weight markers.

FIG. 3. In vitro bioactivity assays. (A) Reduction of viral cytopathic effect (CPE) was performed with encephalomyocarditis virus (EMCV) challenge of A549 cells to determine the anti-viral specific activity of each test compound. The anti-viral titer was determined by comparison of EC₅₀ values with that of an IFNαstandard. (B) Anti-tumor activity was determined by measuring the inhibition of Daudi proliferation in vitro. Dose-response curves were generated from a 4-day MTS assay. The percent of the signal obtained from untreated cells was plotted vs. the log of the concentration in ng/ml. EC50 values were obtained with Graph Pad Prism software. Data shown are representative of multiple repeated experiments.

FIG. 4. Pharmacokinetic (PK) properties were evaluated in Swiss-Webster mice following a single i.v. injection of each agent at equimolar protein dose, with concentrations in serum at various time points determined by ELISA. The data shown represent the mean values from two animals.

FIG. 5. Anti-tumor efficacy in Daudi models. Units of activity were based on in vitro anti-proliferation assay. Injection times are indicated with arrows and median survival is shown for each treatment regimen. (A) Three different doses of each test compound were given s.c. weekly for 4 weeks one day after inoculating Daudi cells. (B) Three different dosing schedules (q7dx4, q2wk×4, and q3wk×4) were evaluated in groups of 6-7 mice administered 4×14,000 U s.c. of PEGINTRON® or α2b-413. (C) Two different dosing schedules (q7dx4 and q4wk×4) were evaluated in groups of 10 mice administered 4×14,000 U s.c. of PEGINTRON® or α2b-413.

FIG. 6. Purity of α2b-457 examined by reducing (R) and nonreducing (NR) SDS-PAGE. Lane 1, CM-purified α2b-457; Lane 2, CM-column fraction −250 mM wash; Lane 3, CM-column fraction-unbound; Lane 4, α2b-413; Lane M, molecular weight markers.

FIG. 7. In vitro bioactivities of α2b-457. (A) Anti-proliferative activity determined by inhibiting Daudi growth. (B) Anti-viral activity determined by CPE. (C) Specific activity determined by reporter gene assay.

FIG. 8. Blood clearance of α2b-413 and α2b-457 after a single s.c. injection in male Swiss-Webster mice.

FIG. 9. Anti-tumor efficacy of α2b-457, α2b-413, and PEGINTRON® in Daudi models. Two different doses of each agent were given s.c. once every 4 weeks. Not all groups received all four injections. Treatment started one day after inoculating Daudi cells.

DOCK AND LOCK (DNL) METHOD

The DNL method is based on the specific protein/protein interactions between the regulatory (R) subunits of cAMP-dependent protein kinase (PKA) and the anchoring domain (AD) of A-kinase anchoring proteins (AKAPs) (Baillie et al., FEBS Letters. 2005; 579: 3264. Wong and Scott, Nat. Rev. Mol. Cell. Biol. 2004; 5: 959). PKA, which plays a central role in the signal transduction pathway triggered by the binding of cAMP to the R subunits of PKA, was first isolated from rabbit skeletal muscle in 1968 (Walsh et al., J. Biol. Chem. 1968; 243:3763). The structure of the holoenzyme consists of two catalytic subunits held in an inactive form by the R subunits (Taylor, J. Biol. Chem. 1989; 264:8443). Isozymes of PKA are found with two types of R subunits (RI and RII), and each type has α and β isoforms (Scott, Pharmacol. Ther. 1991; 50:123). The R subunits have been isolated only as stable dimers and the dimerization domain has been shown to consist of the first 44 amino-terminal residues (Newlon et al., Nat. Struct. Biol. 1999; 6:222). Binding of cAMP to the R subunits leads to the release of active catalytic subunits for a broad spectrum of serine/threonine kinase activities, which are oriented toward selected substrates through the compartmentalization of PKA via its docking with AKAPs (Scott et al., J. Biol. Chem. 1990; 265:21561)

Since the first AKAP, microtubule-associated protein-2, was characterized in 1984 (Lohmann et al., Proc. Natl. Acad. Sci. USA. 1984; 81:6723), more than 50 AKAPs that localize to various sub-cellular sites, including plasma membrane, actin cytoskeleton, nucleus, mitochondria, and endoplasmic reticulum, have been identified with diverse structures in species ranging from yeast to humans (Wong and Scott, Nat. Rev. Mol. Cell. Biol. 2004; 5:959). The AD of AKAPs for PKA is an amphipathic helix of 14-18 residues (Carr et al., J. Biol. Chem. 1991; 266:14188) and any such known AD sequence may be utilized to form a DNL complex. The amino acid sequences of the AD are quite varied among individual AKAPs, with the binding affinities reported for RII dimers ranging from 2 to 90 nM (Alto et al., Proc. Natl. Acad. Sci. USA. 2003; 100:4445). Interestingly, AKAPs will only bind to dimeric R subunits. For human RIIα, the AD binds to a hydrophobic surface formed by the 23 amino-terminal residues (Colledge and Scott, Trends Cell Biol. 1999; 6:216). Thus, the dimerization domain and AKAP binding domain of human RIIα are both located within the same N-terminal 44 amino acid sequence (Newlon et al., Nat. Struct. Biol. 1999; 6:222; Newlon et al., EMBO J. 2001; 20:1651), which is termed the DDD herein.

DDD of Human RIIα and AD of AKAPs as Linker Modules

We have developed a platform technology to utilize the DDD of human RIIα and the AD of AKAPs as an excellent pair of linker modules for docking any two entities, referred to hereafter as A and B, into a noncovalent complex, which could be further locked into a stably tethered structure through the introduction of cysteine residues into both the DDD and AD at strategic positions to facilitate the formation of disulfide bonds. The general methodology of the “dock-and-lock” approach is as follows. Entity A is constructed by linking a DDD sequence to a precursor of A, resulting in a first component hereafter referred to as a. Because the DDD sequence would effect the spontaneous formation of a dimer, A would thus be composed of a₂. Entity B is constructed by linking an AD sequence to a precursor of B, resulting in a second component hereafter referred to as b. The dimeric motif of DDD contained in a₂ will create a docking site for binding to the AD sequence contained in b, thus facilitating a ready association of a₂ and b to form a binary, trimeric complex composed of a₂b. This binding event is made irreversible with a subsequent reaction to covalently secure the two entities via disulfide bridges, which occurs very efficiently based on the principle of effective local concentration because the initial binding interactions bring the reactive thiol groups placed onto both the DDD and AD into proximity (Chmura et al., Proc. Natl. Acad. Sci. USA. 2001; 98:8480) to ligate site-specifically.

By attaching the DDD and AD away from the functional groups of the two precursors, such site-specific ligations are also expected to preserve the original activities of the two precursors. This approach is modular in nature and potentially can be applied to link, site-specifically and covalently, a wide range of substances, including peptides, proteins, nucleic acids, cytokines and PEG.

DDD and AD Sequence Variants

In certain embodiments, the AD and DDD sequences incorporated into the cytokine-PEG DNL complex comprise the amino acid sequences of DDD1 (SEQ ID NO:1) and AD1 (SEQ ID NO:3) below. In more preferred embodiments, the AD and DDD sequences comprise the amino acid sequences of DDD2 (SEQ ID NO:2) and AD2 (SEQ ID NO:4), which are designed to promote disulfide bond formation between the DDD and AD moieties.

DDD1 (SEQ ID NO: 1) SHIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA DDD2 (SEQ ID NO: 2) CGHIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA AD1 (SEQ ID NO:3) QIEYLAKQIVDNAIQQA AD2 (SEQ ID NO: 4) CGQIEYLAKQIVDNAIQQAGC

However, in alternative embodiments sequence variants AD and/or DDD moieties may be utilized in construction of the cytokine-PEG DNL complexes. The structure-function relationships of the AD and DDD domains have been the subject of investigation. (See, e.g., Burns-Hamuro et al., 2005, Protein Sci 14:2982-92; Carr et al., 2001, J Biol Chem 276:17332-38; Alto et al., 2003, Proc Natl Acad Sci USA 100:4445-50; Hundsrucker et al., 2006, Biochem J 396:297-306; Stokka et al., 2006, Biochem J 400:493-99; Gold et al., 2006, Mol Cell 24:383-95; Kinderman et al., 2006, Mol Cell 24:397-408, the entire text of each of which is incorporated herein by reference.)

For example, Kinderman et al. (2006) examined the crystal structure of the AD-DDD binding interaction and concluded that the human DDD sequence contained a number of conserved amino acid residues that were important in either dimer formation or AKAP binding, underlined below in SEQ ID NO:1. (See FIG. 1 of Kinderman et al., 2006, incorporated herein by reference.) The skilled artisan will realize that in designing sequence variants of the DDD sequence, one would desirably avoid changing any of the underlined residues, while conservative amino acid substitutions might be made for residues that are less critical for dimerization and AKAP binding. Thus, a potential alternative DDD sequence of use for construction of DNL complexes is shown in SEQ ID NO:5, wherein “X” represents a conservative amino acid substitution. Conservative amino acid substitutions are discussed in more detail below, but could involve for example substitution of an aspartate residue for a glutamate residue, or a leucine or valine residue for an isoleucine residue, etc. Such conservative amino acid substitutions are well known in the art.

Human DDD sequence from protein kinase A (SEQ ID NO: 1) SHIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA (SEQ ID NO: 5) XXIXIXXXLXXLLXXYXVXVLXXXXXXLVXFXVXYFXXLXXXXX

Alto et al. (2003) performed a bioinformatic analysis of the AD sequence of various AKAP proteins to design an RII selective AD sequence called AKAP-IS (SEQ ID NO:3), with a binding constant for DDD of 0.4 nM. The AKAP-IS sequence was designed as a peptide antagonist of AKAP binding to PKA. Residues in the AKAP-IS sequence where substitutions tended to decrease binding to DDD are underlined in SEQ ID NO:3. Therefore, the skilled artisan will realize that variants which may function for DNL constructs are indicated by SEQ ID NO:6, where “X” is a conservative amino acid substitution.

AKAP-IS sequence (SEQ ID NO: 3) QIEYLAKQIVDNAIQQA (SEQ ID NO: 6) XXXXXAXXIVXXAIXXX

Similarly, Gold (2006) utilized crystallography and peptide screening to develop a SuperAKAP-IS sequence (SEQ ID NO:7), exhibiting a five order of magnitude higher selectivity for the RH isoform of PKA compared with the RI isoform. Underlined residues indicate the positions of amino acid substitutions, relative to the AKAP-IS sequence, that increased binding to the DDD moiety of RIIα. In this sequence, the N-terminal Q residue is numbered as residue number 4 and the C-terminal A residue is residue number 20. Residues where substitutions could be made to affect the affinity for RIIα were residues 8, 11, 15, 16, 18, 19 and 20 (Gold et al., 2006). It is contemplated that in certain alternative embodiments, the SuperAKAP-IS sequence may be substituted for the AKAP-IS AD moiety sequence to prepare cytokine-PEG DNL constructs. Other alternative sequences that might be substituted for the AKAP-IS AD sequence are shown in SEQ ID NO:8-10. Substitutions relative to the AKAP-IS sequence are underlined. It is anticipated that, as with the AKAP-IS sequence shown in SEQ ID NO:3, the AD moiety may also include the additional N-terminal residues cysteine and glycine and C-terminal residues glycine and cysteine, as shown in SEQ ID NO:4.

SuperAKAP-IS (SEQ ID NO: 7) QIEYVAKQIVDYAIHQA Alternative AKAP sequences (SEQ ID NO: 8) QIEYKAKQIVDHAIHQA (SEQ ID NO: 9) QIEYHAKQIVDHAIHQA (SEQ ID NO: 10) QIEYVAKQIVDHAIHQA

Stokka et al. (2006) also developed peptide competitors of AKAP binding to PKA, shown in SEQ ID NO:11-13. The peptide antagonists were designated as Ht31 (SEQ ID NO:11), RIAD (SEQ ID NO:12) and PV-38 (SEQ ID NO:13). The Ht-31 peptide exhibited a greater affinity for the RH isoform of PKA, while the RIAD and PV-38 showed higher affinity for RI.

Ht31 (SEQ ID NO: 11) DLIEEAASRIVDAVIEQVKAAGAY RIAD (SEQ ID NO:12) LEQYANQLADQIIKEATE PV-38 (SEQ ID NO:13) FEELAWKIAKMIWSDVFQQC

Hundsrucker et al. (2006) developed still other peptide competitors for AKAP binding to PKA, with a binding constant as low as 0.4 nM to the DDD of the RII form of PKA. The sequences of various AKAP antagonistic peptides is provided in Table 1 of Hundsrucker et al. (incorporated herein by reference). Residues that were highly conserved among the AD domains of different AKAP proteins are indicated below by underlining with reference to the AKAP IS sequence (SEQ ID NO:3). The residues are the same as observed by Alto et al. (2003), with the addition of the C-terminal alanine residue. (See FIG. 4 of Hundsrucker et al. (2006), incorporated herein by reference.) The sequences of peptide antagonists with particularly high affinities for the RH DDD sequence are shown in SEQ ID NO:14-16.

AKAP-IS (SEQ ID NO: 3) QIEYLAKQIVDNAIQQA AKAP7δ-wt-pep (SEQ ID NO: 14) PEDAELVRLSKRLVENAVLKAVQQY AKAP7δ-L304T-pep (SEQ ID NO: 15) PEDAELVRTSKRLVENAVLKAVQQY AKAP7δ-L308D-pep (SEQ ID NO: 16) PEDAELVRLSKRDVENAVLKAVQQY

Carr et al. (2001) examined the degree of sequence homology between different AKAP-binding DDD sequences from human and non-human proteins and identified residues in the DDD sequences that appeared to be the most highly conserved among different DDD moieties. These are indicated below by underlining with reference to the human PKA RIIα DDD sequence of SEQ ID NO:1. Residues that were particularly conserved are further indicated by italics. The residues overlap with, but are not identical to those suggested by Kinderman et al. (2006) to be important for binding to AKAP proteins. Thus, a potential DDD sequence is indicated in SEQ ID NO:17, wherein “X” represents a conservative amino acid substitution.

(SEQ ID NO: 1) SHIQ IP P GL TELLQGYT V EVLR Q QP P DLVEFA VE YF TR L REA R A (SEQ ID NO: 17) XHIX IP X GL XELLQGYT X EVLR X QP X DLVEFA XX YF XX L XEX R X

The skilled artisan will realize that in general, those amino acid residues that are highly conserved in the DDD and AD sequences from different proteins are ones that it may be preferred to remain constant in making amino acid substitutions, while residues that are less highly conserved may be more easily varied to produce sequence variants of the AD and/or DDD sequences described herein.

In addition to sequence variants of the DDD and/or AD moieties, in certain embodiments it may be preferred to introduce sequence variations in the antibody moiety or the linker peptide sequence joining the antibody with the AD sequence. In one illustrative example, three possible variants of fusion protein sequences, are shown in SEQ ID NO:18-20.

(L) (SEQ ID NO: 18) QKSLSLSPGLGSGGGGSGGCG (A) (SEQ ID NO: 19) QKSLSLSPGAGSGGGGSGGCG (−) (SEQ ID NO: 20) QKSLSLSPGGSGGGGSGGCG

PEGylation by DNL

In a preferred method, the therapeutic agent to be PEGylated is linked to a DDD sequence to generate the DDD module. A PEG reagent of a desirable molecular size is derivatized with a related AD sequence and the resulting PEG-AD module is combined with the DDD module to produce the PEGylated conjugate that consists of a single PEG tethered site-specifically to two copies of the therapeutic agent via the disulfide bonds formed between DDD and AD. The PEG reagents may be capped at one end with a methoxy group (m-PEG), can be linear or branched, and may contain one of the following functional groups: propionic aldehyde, butyric aldehyde, ortho-pyridylthioester (OPTE), N-hydroxysuccinimide (NHS), thiazolidine-2-thione, succinimidyl carbonate (SC), maleimide, or ortho-pyridyldisulfide (OPPS). Among the agents that may be of interest for PEGylation are cytokines, enzymes, chemokines, growth factors, peptides, aptamers, hemoglobins, antibodies and fragments. The method is not limiting and a wide variety of agents may be PEGylated using the disclosed methods and compositions.

Cytokines and Other Immunomodulators

In certain preferred embodiments, the effector moiety is an immunomodulator. An immunomodulator is an agent that when present, alters, suppresses or stimulates the body's immune system. Immunomodulators of use may include a cytokine, a stem cell growth factor, a lymphotoxin, a hematopoietic factor, a colony stimulating factor (CSF), an interferon (IFN), erythropoietin, thrombopoietin and a combination thereof. Specifically useful are lymphotoxins such as tumor necrosis factor (TNF), hematopoietic factors, such as interleukin (IL), colony stimulating factor, such as granulocyte-colony stimulating factor (G-CSF) or granulocyte macrophage-colony stimulating factor (GM-CSF), interferon, such as interferons-α, -β or -γ, and stem cell growth factor, such as that designated “S1 factor”.

In more preferred embodiments, the effector moieties are cytokines, such as lymphokines, monokines, growth factors and traditional polypeptide hormones. Included among the cytokines are growth hormones such as human growth hormone, N-methionyl human growth hormone, and bovine growth hormone; parathyroid hormone; thyroxine; insulin; proinsulin; relaxin; prorelaxin; glycoprotein hormones such as follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), and luteinizing hormone (LH); placenta growth factor (PlGF), hepatic growth factor; prostaglandin, fibroblast growth factor; prolactin; placental lactogen, OB protein; tumor necrosis factor-α and -β; mullerian-inhibiting substance; mouse gonadotropin-associated peptide; inhibin; activin; vascular endothelial growth factor; integrin; thrombopoietin (TPO); nerve growth factors such as NGF-β; platelet-growth factor; transforming growth factors (TGFs) such as TGF-α and TGF-β; insulin-like growth factor-I and -II; erythropoietin (EPO); osteoinductive factors; interferons such as interferon-α, -β, and -γ; colony stimulating factors (CSFs) such as macrophage-CSF (M-CSF); interleukins (ILs) such as IL-1, IL-1α, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12; IL-13, IL-14, IL-15, IL-16, IL-17, IL-18, IL-21, IL-25, LIF, kit-ligand or FLT-3, angiostatin, thrombospondin, endostatin, tumor necrosis factor (TNF, such as TNF-α) and LT. In a particularly preferred embodiment, the cytokine is IFN-α2b.

The amino acid sequences of protein or peptide immunomodulators, such as cytokines, are well known in the art and any such known sequences may be used in the practice of the instant invention. The skilled artisan is aware of numerous sources of public information on cytokine sequence. For example, the NCBI database contains both protein and encoding nucleic acid sequences for a large number of cytokines and immunomodulators, such as erythropoietin (GenBank NM 000799), IL-1 beta (GenPept AAH08678), GM-CSF (GenPept AAA52578), TNF-α (GenPept CAA26669), interferon-alpha (GenPept AAA52716.1), interferon-alpha 2b (GenPept AAP20099.1) and virtually any of the peptide or protein immunomodulators listed above. It is a matter of routine for the skilled artisan to identify an appropriate amino acid and/or nucleic acid sequence for essentially any protein or peptide effector moiety of interest. Commercial sources of cytokines are also available and may be used, such as the full-length human IFN-α2b cDNA clone (Invitrogen Ultimate ORF human clone cat#HORF01Clone ID IOH35221).

Antibodies

In certain embodiments, an antibody or antigen binding fragment thereof may be incorporated into a DNL construct, such as by PEGylation of an antibody or fragment, or by attachment of an antibody or fragment to a cytokine for targeted delivery of the cytokine. Any known antibody or antigen-binding fragment thereof may be incorporated into a DNL construct. In preferred embodiments, the complex is of use for cancer therapy and the antibody binds to a tumor associated antigen (TAA). A variety of tumor-associated antigens are known in the art, including but not limited to carbonic anhydrase IX, CCCL19, CCCL21, CSAp, CD1, CD1a, CD2, CD3, CD4, CD5, CD8, CD11A, CD14, CD15, CD16, CD18, CD19, IGF-1R, CD20, CD21, CD22, CD23, CD25, CD29, CD30, CD32b, CD33, CD37, CD38, CD40, CD40L, CD45, CD46, CD52, CD54, CD55, CD59, CD64, CD66a-e, CD67, CD70, CD74, CD79a, CD80, CD83, CD95, CD126, CD133, CD138, CD147, CD154, AFP, PSMA, CEACAM5, CEACAM-6, B7, ED-B of fibronectin, Factor H, FHL-1, Flt-3, folate receptor, GROB, HMGB-1, hypoxia inducible factor (RIF), HM1.24, insulin-like growth factor-1 (ILGF-1), IFN-γ, IFN-β, IL-2, IL-4R, IL-6R, IL-13R, IL-15R, IL-17R, IL-18R, IL-6, IL-8, IL-12, IL-15, IL-17, IL-18, IL-25, IP-10, MAGE, mCRP, MCP-1, MIP-1A, MIP-1B, MIF, MUC1, MUC2, MUC3, MUC4, MUC5, PAM4 antigen, NCA-95, NCA-90, Ia, HM1.24, EGP-1, EGP-2, HLA-DR, tenascin, Le(y), RANTES, T101, TAC, Tn antigen, Thomson-Friedenreich antigens, tumor necrosis antigens, TNF-α, TRAIL receptor (R1 and R2), VEGFR, EGFR, P1GF, complement factors C3, C3a, C3b, C5a, C5, and an oncogene product. Other types of target antigen are of use for antibody-based therapy of different disease states and DNL constructs incorporating antibodies that target any such alternative antigen may be utilized.

Exemplary anti-cancer antibodies that may be utilized in DNL constructs include, but are not limited to, hR1 (anti-IGF-1R, U.S. Provisional Patent Application Ser. No. 61/145,896, filed Jan. 20, 2009) hPAM4 (anti-MUC1, U.S. Pat. No. 7,282,567), hA20 (anti-CD20, U.S. Pat. No. 7,251,164), hA19 (anti-CD19, U.S. Pat. No. 7,109,304), hIMMU31 (anti-AFP, U.S. Pat. No. 7,300,655), hLL1 (anti-CD74, U.S. Pat. No. 7,312,318), hLL2 (anti-CD22, U.S. Pat. No. 7,074,403), hMu-9 (anti-CSAp, U.S. Pat. No. 7,387,773), hL243 (anti-HLA-DR, U.S. Pat. No. 7,612,180), hMN-14 (anti-CEA, U.S. Pat. No. 6,676,924), hMN-15 (anti-CEA, U.S. patent application Ser. No. 10/672,278), hRS7 (anti-EGP-1, U.S. Pat. No. 7,238,785) and hMN-3 (anti-CEA, U.S. Pat. No. 7,541,440) the Examples section of each cited patent or application incorporated herein by reference. The skilled artisan will realize that this list is not limiting and any other known anti-TAA antibody may be incorporated into the DNL constructs.

Antigen-binding antibody fragments are well known in the art, such as F(ab′)₂, F(ab)₂, Fab′, Fab, Fv, scFv and the like, and any such known fragment may be used. As used herein, an antigen-binding antibody fragment refers to any fragment of an antibody that binds with the same antigen that is recognized by the intact or parent antibody. Techniques for preparing AD and/or DDD conjugates of virtually any antibody or fragment of interest are known (e.g., U.S. Pat. No. 7,527,787).

An antibody or fragment thereof may be used which is not conjugated to a therapeutic agent is referred to as a “naked” antibody or fragment thereof. In alternative embodiments, antibodies or fragments may be conjugated to one or more therapeutic and/or diagnostic agents. A wide variety of such therapeutic and diagnostic agents are known in the art, as discussed in more detail below, and any such known therapeutic or diagnostic agent may be used.

Techniques for preparing monoclonal antibodies against virtually any target antigen are well known in the art. See, for example, Kohler and Milstein, Nature 256: 495 (1975), and Coligan et al. (eds.), CURRENT PROTOCOLS IN IMMUNOLOGY, VOL. 1, pages 2.5.1-2.6.7 (John Wiley & Sons 1991). Briefly, monoclonal antibodies can be obtained by injecting mice with a composition comprising an antigen, removing the spleen to obtain B-lymphocytes, fusing the B-lymphocytes with myeloma cells to produce hybridomas, cloning the hybridomas, selecting positive clones which produce antibodies to the antigen, culturing the clones that produce antibodies to the antigen, and isolating the antibodies from the hybridoma cultures.

MAbs can be isolated and purified from hybridoma cultures by a variety of well-established techniques. Such isolation techniques include affinity chromatography with Protein-A Sepharose, size-exclusion chromatography, and ion-exchange chromatography. See, for example, Coligan at pages 2.7.1-2.7.12 and pages 2.9.1-2.9.3. Also, see Baines et al., “Purification of Immunoglobulin G (IgG),” in METHODS IN MOLECULAR BIOLOGY, VOL. 10, pages 79-104 (The Humana Press, Inc. 1992).

After the initial raising of antibodies to the immunogen, the antibodies can be sequenced and subsequently prepared by recombinant techniques. Humanization and chimerization of murine antibodies and antibody fragments are well known to those skilled in the art. The use of antibody components derived from humanized, chimeric or human antibodies obviates potential problems associated with the immunogenicity of murine constant regions.

Chimeric Antibodies

A chimeric antibody is a recombinant protein in which the variable regions of a human antibody have been replaced by the variable regions of, for example, a mouse antibody, including the complementarity-determining regions (CDRs) of the mouse antibody. Chimeric antibodies exhibit decreased immunogenicity and increased stability when administered to a subject. General techniques for cloning murine immunoglobulin variable domains are disclosed, for example, in Orlandi et al., Proc. Nat'l Acad. Sci. USA 86: 3833 (1989). Techniques for constructing chimeric antibodies are well known to those of skill in the art. As an example, Leung et al., Hybridoma 13:469 (1994), produced an LL2 chimera by combining DNA sequences encoding the V_(κ) and V_(H) domains of murine LL2, an anti-CD22 monoclonal antibody, with respective human κ and IgG₁ constant region domains.

Humanized Antibodies

Techniques for producing humanized MAbs are well known in the art (see, e.g., Jones et al., Nature 321: 522 (1986), Riechmann et al., Nature 332: 323 (1988), Verhoeyen et al., Science 239: 1534 (1988), Carter et al., Proc. Nat'l Acad. Sci. USA 89: 4285 (1992), Sandhu, Crit. Rev. Biotech. 12: 437 (1992), and Singer et al., J. Immun. 150: 2844 (1993)). A chimeric or murine monoclonal antibody may be humanized by transferring the mouse CDRs from the heavy and light variable chains of the mouse immunoglobulin into the corresponding variable domains of a human antibody. The mouse framework regions (FR) in the chimeric monoclonal antibody are also replaced with human FR sequences. As simply transferring mouse CDRs into human FRs often results in a reduction or even loss of antibody affinity, additional modification might be required in order to restore the original affinity of the murine antibody. This can be accomplished by the replacement of one or more human residues in the FR regions with their murine counterparts to obtain an antibody that possesses good binding affinity to its epitope. See, for example, Tempest et al., Biotechnology 9:266 (1991) and Verhoeyen et al., Science 239: 1534 (1988). Generally, those human FR amino acid residues that differ from their murine counterparts and are located close to or touching one or more CDR amino acid residues would be candidates for substitution.

Human Antibodies

Methods for producing fully human antibodies using either combinatorial approaches or transgenic animals transformed with human immunoglobulin loci are known in the art (e.g., Mancini et al., 2004, New Microbiol. 27:315-28; Conrad and Scheller, 2005, Comb. Chem. High Throughput Screen. 8:117-26; Brekke and Loset, 2003, Curr. Opin. Phamacol. 3:544-50). A fully human antibody also can be constructed by genetic or chromosomal transfection methods, as well as phage display technology, all of which are known in the art. See for example, McCafferty et al., Nature 348:552-553 (1990). Such fully human antibodies are expected to exhibit even fewer side effects than chimeric or humanized antibodies and to function in vivo as essentially endogenous human antibodies. In certain embodiments, the claimed methods and procedures may utilize human antibodies produced by such techniques.

In one alternative, the phage display technique may be used to generate human antibodies (e.g., Dantas-Barbosa et al., 2005, Genet. Mol. Res. 4:126-40). Human antibodies may be generated from normal humans or from humans that exhibit a particular disease state, such as cancer (Dantas-Barbosa et al., 2005). The advantage to constructing human antibodies from a diseased individual is that the circulating antibody repertoire may be biased towards antibodies against disease-associated antigens.

In one non-limiting example of this methodology, Dantas-Barbosa et al. (2005) constructed a phage display library of human Fab antibody fragments from osteosarcoma patients. Generally, total RNA was obtained from circulating blood lymphocytes (Id.). Recombinant Fab were cloned from the μ, γ and κ chain antibody repertoires and inserted into a phage display library (Id.). RNAs were converted to cDNAs and used to make Fab cDNA libraries using specific primers against the heavy and light chain immunoglobulin sequences (Marks et al., 1991, J. Mol. Biol. 222:581-97). Library construction was performed according to Andris-Widhopf et al. (2000, In: Phage Display Laboratory Manual, Barbas et al. (eds), 1^(st) edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. pp. 9.1 to 9.22). The final Fab fragments were digested with restriction endonucleases and inserted into the bacteriophage genome to make the phage display library. Such libraries may be screened by standard phage display methods, as known in the art (see, e.g., Pasqualini and Ruoslahti, 1996, Nature 380:364-366; Pasqualini, 1999, The Quart. J. Nucl. Med. 43:159-162).

Phage display can be performed in a variety of formats, for their review, see e.g. Johnson and Chiswell, Current Opinion in Structural Biology 3:5564-571 (1993). Human antibodies may also be generated by in vitro activated B-cells. See U.S. Pat. Nos. 5,567,610 and 5,229,275, incorporated herein by reference in their entirety. The skilled artisan will realize that these techniques are exemplary and any known method for making and screening human antibodies or antibody fragments may be utilized.

In another alternative, transgenic animals that have been genetically engineered to produce human antibodies may be used to generate antibodies against essentially any immunogenic target, using standard immunization protocols. Methods for obtaining human antibodies from transgenic mice are disclosed by Green et al., Nature Genet. 7:13 (1994), Lonberg et al., Nature 368:856 (1994), and Taylor et al., Int. Immun. 6:579 (1994). A non-limiting example of such a system is the XenoMouse® (e.g., Green et al., 1999, J. Immunol. Methods 231:11-23) from Abgenix (Fremont, Calif.). In the XenoMouse® and similar animals, the mouse antibody genes have been inactivated and replaced by functional human antibody genes, while the remainder of the mouse immune system remains intact.

The XenoMouse® was transformed with germline-configured YACs (yeast artificial chromosomes) that contained portions of the human IgH and Igkappa loci, including the majority of the variable region sequences, along accessory genes and regulatory sequences. The human variable region repertoire may be used to generate antibody producing B-cells, which may be processed into hybridomas by known techniques. A XenoMouse® immunized with a target antigen will produce human antibodies by the normal immune response, which may be harvested and/or produced by standard techniques discussed above. A variety of strains of XenoMouse® are available, each of which is capable of producing a different class of antibody. Transgenically produced human antibodies have been shown to have therapeutic potential, while retaining the pharmacokinetic properties of normal human antibodies (Green et al., 1999). The skilled artisan will realize that the claimed compositions and methods are not limited to use of the XenoMouse® system but may utilize any transgenic animal that has been genetically engineered to produce human antibodies.

Antibody Fragments

Antibody fragments which recognize specific epitopes can be generated by known techniques. Antibody fragments are antigen binding portions of an antibody, such as F(ab′)₂, Fab′, F(ab)₂, Fab, Fv, sFv and the like. F(ab′)₂ fragments can be produced by pepsin digestion of the antibody molecule and Fab′ fragments can be generated by reducing disulfide bridges of the F(ab′)₂ fragments. Alternatively, Fab′ expression libraries can be constructed (Huse et al., 1989, Science, 246:1274-1281) to allow rapid and easy identification of monoclonal Fab′ fragments with the desired specificity. F(ab)₂ fragments may be generated by papain digestion of an antibody and Fab fragments obtained by disulfide reduction.

A single chain Fv molecule (scFv) comprises a VL domain and a VH domain. The VL and VH domains associate to form a target binding site. These two domains are further covalently linked by a peptide linker (L). Methods for making scFv molecules and designing suitable peptide linkers are described in U.S. Pat. No. 4,704,692, U.S. Pat. No. 4,946,778, R. Raag and M. Whitlow, “Single Chain Fvs.” FASEB Vol 9:73-80 (1995) and R. E. Bird and B. W. Walker, “Single Chain Antibody Variable Regions,” TIBTECH, Vol 9: 132-137 (1991).

Techniques for producing single domain antibodies (DABs) are also known in the art, as disclosed for example in Cossins et al. (2006, Prot Express Purif 51:253-259), incorporated herein by reference.

An antibody fragment can be prepared by proteolytic hydrolysis of the full length antibody or by expression in E. coli or another host of the DNA coding for the fragment. An antibody fragment can be obtained by pepsin or papain digestion of full length antibodies by conventional methods. These methods are described, for example, by Goldenberg, U.S. Pat. Nos. 4,036,945 and 4,331,647 and references contained therein. Also, see Nisonoff et al., Arch Biochem. Biophys. 89: 230 (1960); Porter, Biochem. J. 73: 119 (1959), Edelman et al., in METHODS IN ENZYMOLOGY VOL. 1, page 422 (Academic Press 1967), and Coligan at pages 2.8.1-2.8.10 and 2.10.-2.10.4.

Known Antibodies

Antibodies of use may be commercially obtained from a wide variety of known sources. For example, a variety of antibody secreting hybridoma lines are available from the American Type Culture Collection (ATCC, Manassas, Va.). A large number of antibodies against various disease targets, including but not limited to tumor-associated antigens, have been deposited at the ATCC and/or have published variable region sequences and are available for use in the claimed methods and compositions. See, e.g., U.S. Pat. Nos. 7,312,318; 7,282,567; 7,151,164; 7,074,403; 7,060,802; 7,056,509; 7,049,060; 7,045,132; 7,041,803; 7,041,802; 7,041,293; 7,038,018; 7,037,498; 7,012,133; 7,001,598; 6,998,468; 6,994,976; 6,994,852; 6,989,241; 6,974,863; 6,965,018; 6,964,854; 6,962,981; 6,962,813; 6,956,107; 6,951,924; 6,949,244; 6,946,129; 6,943,020; 6,939,547; 6,921,645; 6,921,645; 6,921,533; 6,919,433; 6,919,078; 6,916,475; 6,905,681; 6,899,879; 6,893,625; 6,887,468; 6,887,466; 6,884,594; 6,881,405; 6,878,812; 6,875,580; 6,872,568; 6,867,006; 6,864,062; 6,861,511; 6,861,227; 6,861,226; 6,838,282; 6,835,549; 6,835,370; 6,824,780; 6,824,778; 6,812,206; 6,793,924; 6,783,758; 6,770,450; 6,767,711; 6,764,688; 6,764,681; 6,764,679; 6,743,898; 6,733,981; 6,730,307; 6,720,155; 6,716,966; 6,709,653; 6,693,176; 6,692,908; 6,689,607; 6,689,362; 6,689,355; 6,682,737; 6,682,736; 6,682,734; 6,673,344; 6,653,104; 6,652,852; 6,635,482; 6,630,144; 6,610,833; 6,610,294; 6,605,441; 6,605,279; 6,596,852; 6,592,868; 6,576,745; 6,572,856; 6,566,076; 6,562,618; 6,545,130; 6,544,749; 6,534,058; 6,528,625; 6,528,269; 6,521,227; 6,518,404; 6,511,665; 6,491,915; 6,488,930; 6,482,598; 6,482,408; 6,479,247; 6,468,531; 6,468,529; 6,465,173; 6,461,823; 6,458,356; 6,455,044; 6,455,040, 6,451,310; 6,444,206; 6,441,143; 6,432,404; 6,432,402; 6,419,928; 6,413,726; 6,406,694; 6,403,770; 6,403,091; 6,395,276; 6,395,274; 6,387,350; 6,383,759; 6,383,484; 6,376,654; 6,372,215; 6,359,126; 6,355,481; 6,355,444; 6,355,245; 6,355,244; 6,346,246; 6,344,198; 6,340,571; 6,340,459; 6,331,175; 6,306,393; 6,254,868; 6,187,287; 6,183,744; 6,129,914; 6,120,767; 6,096,289; 6,077,499; 5,922,302; 5,874,540; 5,814,440; 5,798,229; 5,789,554; 5,776,456; 5,736,119; 5,716,595; 5,677,136; 5,587,459; 5,443,953, 5,525,338. These are exemplary only and a wide variety of other antibodies and their hybridomas are known in the art. The skilled artisan will realize that antibody sequences or antibody-secreting hybridomas against almost any disease-associated antigen may be obtained by a simple search of the ATCC, NCBI and/or USPTO databases for antibodies against a selected disease-associated target of interest. The antigen binding domains of the cloned antibodies may be amplified, excised, ligated into an expression vector, transfected into an adapted host cell and used for protein production, using standard techniques well known in the art.

Amino Acid Substitutions

In certain embodiments, the disclosed methods and compositions may involve production and use of proteins or peptides with one or more substituted amino acid residues. In a non-limiting example, the DDD and/or AD sequences used to make the cytokine-PEG DNL constructs may be further optimized, for example to increase the DDD-AD binding affinity.

The skilled artisan will be aware that, in general, amino acid substitutions typically involve the replacement of an amino acid with another amino acid of relatively similar properties (i.e., conservative amino acid substitutions). The properties of the various amino acids and effect of amino acid substitution on protein structure and function have been the subject of extensive study and knowledge in the art.

For example, the hydropathic index of amino acids may be considered (Kyte & Doolittle, 1982, J. Mol. Biol., 157:105-132). The relative hydropathic character of the amino acid contributes to the secondary structure of the resultant protein, which in turn defines the interaction of the protein with other molecules. Each amino acid has been assigned a hydropathic index on the basis of its hydrophobicity and charge characteristics (Kyte & Doolittle, 1982), these are: isoleucine (+4.5); valine (+4.2); leucine (+3.8); phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine (−0.4); threonine (−0.7); serine (−0.8); tryptophan (−0.9); tyrosine (−1.3); proline (−1.6); histidine (−3.2); glutamate (−3.5); glutamine (−3.5); aspartate (−3.5); asparagine (−3.5); lysine (−3.9); and arginine (−4.5). In making conservative substitutions, the use of amino acids whose hydropathic indices are within ±2 is preferred, within ±1 are more preferred, and within ±0.5 are even more preferred.

Amino acid substitution may also take into account the hydrophilicity of the amino acid residue (e.g., U.S. Pat. No. 4,554,101). Hydrophilicity values have been assigned to amino acid residues: arginine (+3.0); lysine (+3.0); aspartate (+3.0); glutamate (+3.0); serine (+0.3); asparagine (+0.2); glutamine (+0.2); glycine (0); threonine (−0.4); proline (−0.5 .+−0.1); alanine (−0.5); histidine (−0.5); cysteine (−1.0); methionine (−1.3); valine (−1.5); leucine (−1.8); isoleucine (−1.8); tyrosine (−2.3); phenylalanine (−2.5); tryptophan (−3.4). Replacement of amino acids with others of similar hydrophilicity is preferred.

Other considerations include the size of the amino acid side chain. For example, it would generally not be preferred to replace an amino acid with a compact side chain, such as glycine or serine, with an amino acid with a bulky side chain, e.g., tryptophan or tyrosine. The effect of various amino acid residues on protein secondary structure is also a consideration. Through empirical study, the effect of different amino acid residues on the tendency of protein domains to adopt an alpha-helical, beta-sheet or reverse turn secondary structure has been determined and is known in the art (see, e.g., Chou & Fasman, 1974, Biochemistry, 13:222-245; 1978, Ann. Rev. Biochem., 47: 251-276; 1979, Biophys. J., 26:367-384).

Based on such considerations and extensive empirical study, tables of conservative amino acid substitutions have been constructed and are known in the art. For example: arginine and lysine; glutamate and aspartate; serine and threonine; glutamine and asparagine; and valine, leucine and isoleucine. Alternatively: Ala (A) leu, ile, val; Arg (R) gln, asn, lys; Asn (N) his, asp, lys, arg, gln; Asp (D) asn, glu; Cys (C) ala, ser; Gln (Q) glu, asn; Glu (E) gln, asp; Gly (G) ala; His (H) asn, gln, lys, arg; Ile (I) val, met, ala, phe, leu; Leu (L) val, met, ala, phe, ile; Lys (K) gln, asn, arg; Met (M) phe, ile, leu; Phe (F) leu, val, ile, ala, tyr; Pro (P) ala; Ser (S), thr; Thr (T) ser; Trp (W) phe, tyr; Tyr (Y) trp, phe, thr, ser; Val (V) ile, leu, met, phe, ala.

Other considerations for amino acid substitutions include whether or not the residue is located in the interior of a protein or is solvent exposed. For interior residues, conservative substitutions would include: Asp and Asn; Ser and Thr; Ser and Ala; Thr and Ala; Ala and Gly; Ile and Val; Val and Leu; Leu and Ile; Leu and Met; Phe and Tyr; Tyr and Trp. (See, e.g., PROWL website at rockefeller.edu) For solvent exposed residues, conservative substitutions would include: Asp and Asn; Asp and Glu; Glu and Gln; Glu and Ala; Gly and Asn; Ala and Pro; Ala and Gly; Ala and Ser; Ala and Lys; Ser and Thr; Lys and Arg; Val and Leu; Leu and Ile; Ile and Val; Phe and Tyr. (Id.) Various matrices have been constructed to assist in selection of amino acid substitutions, such as the PAM250 scoring matrix, Dayhoff matrix, Grantham matrix, McLachlan matrix, Doolittle matrix, Henikoff matrix, Miyata matrix, Fitch matrix, Jones matrix, Rao matrix, Levin matrix and Risler matrix (Idem.)

In determining amino acid substitutions, one may also consider the existence of intermolecular or intramolecular bonds, such as formation of ionic bonds (salt bridges) between positively charged residues (e.g., His, Arg, Lys) and negatively charged residues (e.g., Asp, Glu) or disulfide bonds between nearby cysteine residues.

Methods of substituting any amino acid for any other amino acid in an encoded protein sequence are well known and a matter of routine experimentation for the skilled artisan, for example by the technique of site-directed mutagenesis or by synthesis and assembly of oligonucleotides encoding an amino acid substitution and splicing into an expression vector construct.

Therapeutic Agents

In various embodiments, therapeutic agents such as cytotoxic agents, anti-angiogenic agents, pro-apoptotic agents, antibiotics, hormones, hormone antagonists, chemokines, drugs, prodrugs, toxins, enzymes or other agents may be used as adjunct therapies to the cytokine-PEG DNL constructs described herein. Drugs of use may possess a pharmaceutical property selected from the group consisting of antimitotic, antikinase, alkylating, antimetabolite, antibiotic, alkaloid, anti-angiogenic, pro-apoptotic agents and combinations thereof.

Exemplary drugs of use may include 5-fluorouracil, aplidin, azaribine, anastrozole, anthracyclines, bendamustine, bleomycin, bortezomib, bryostatin-1, busulfan, calicheamycin, camptothecin, carboplatin, 10-hydroxycamptothecin, carmustine, celebrex, chlorambucil, cisplatin (CDDP), Cox-2 inhibitors, irinotecan (CPT-11), SN-38, carboplatin, cladribine, camptothecans, cyclophosphamide, cytarabine, dacarbazine, docetaxel, dactinomycin, daunorubicin, doxorubicin, 2-pyrrolinodoxorubicine (2P-DOX), cyano-morpholino doxorubicin, doxorubicin glucuronide, epirubicin glucuronide, estramustine, epipodophyllotoxin, estrogen receptor binding agents, etoposide (VP16), etoposide glucuronide, etoposide phosphate, floxuridine (FUdR), 3′,5′-O-dioleoyl-FudR (FUdR-dO), fludarabine, flutamide, farnesyl-protein transferase inhibitors, gemcitabine, hydroxyurea, idarubicin, ifosfamide, L-asparaginase, lenolidamide, leucovorin, lomustine, mechlorethamine, melphalan, mercaptopurine, 6-mercaptopurine, methotrexate, mitoxantrone, mithramycin, mitomycin, mitotane, navelbine, nitrosourea, plicamycin, procarbazine, paclitaxel, pentostatin, PSI-341, raloxifene, semustine, streptozocin, tamoxifen, taxol, temazolomide (an aqueous form of DTIC), transplatinum, thalidomide, thioguanine, thiotepa, teniposide, topotecan, uracil mustard, vinorelbine, vinblastine, vincristine and vinca alkaloids.

Toxins of use may include ricin, abrin, alpha toxin, saporin, ribonuclease (RNase), e.g., onconase, DNase I, Staphylococcal enterotoxin-A, pokeweed antiviral protein, gelonin, diphtheria toxin, Pseudomonas exotoxin, and Pseudomonas endotoxin.

Chemokines of use may include RANTES, MCAF, MIP1-Beta and IP-10.

In certain embodiments, anti-angiogenic agents, such as angiostatin, baculostatin, canstatin, maspin, anti-VEGF antibodies, anti-P1GF peptides and antibodies, anti-vascular growth factor antibodies, anti-Flk-1 antibodies, anti-Flt-1 antibodies and peptides, anti-Kras antibodies, anti-cMET antibodies, anti-MIF (macrophage migration-inhibitory factor) antibodies, laminin peptides, fibronectin peptides, plasminogen activator inhibitors, tissue metalloproteinase inhibitors, interferons, interleukin-12, IP-10, Gro-13, thrombospondin, 2-methoxyoestradiol, proliferin-related protein, carboxiamidotriazole, CM101, Marimastat, pentosan polysulphate, angiopoietin-2, interferon-alpha, herbimycin A, PNU145156E, 16K prolactin fragment, Linomide (roquinimex), thalidomide, pentoxifylline, genistein, TNP-470, endostatin, paclitaxel, accutin, angiostatin, cidofovir, vincristine, bleomycin, AGM-1470, platelet factor 4 or minocycline may be of use.

Other useful therapeutic agents may comprise oligonucleotides, especially antisense oligonucleotides that preferably are directed against oncogenes and oncogene products, such as bcl-2 or p53. A preferred form of therapeutic oligonucleotide is siRNA.

Diagnostic Agents

Diagnostic agents are preferably selected from the group consisting of a radionuclide, a radiological contrast agent, a paramagnetic ion, a metal, a fluorescent label, a chemiluminescent label, an ultrasound contrast agent and a photoactive agent. Such diagnostic agents are well known and any such known diagnostic agent may be used. Non-limiting examples of diagnostic agents may include a radionuclide such as ¹¹⁰In, ¹¹¹In, ¹⁸F, ⁵²Fe, ⁶²Cu, ⁶⁴Cu, ⁶⁷Cu, ⁶⁷Ga, ⁶⁸Ga, ⁸⁶Y, ⁹⁰Y, ⁸⁹Zr, ^(94m)Tc, ⁹⁴Tc, ^(99m)Tc, ¹²⁰I, ¹²³I, ¹²⁴I, ¹²⁵I, ¹³¹I, ¹⁵⁴⁻¹⁵⁸Gd, ³²P, ¹¹C, ¹³N, ¹⁵O, ¹⁸⁶Re, ¹⁸⁸Re, ⁵¹Mn, ^(52m)Mn, ⁵⁵Co, ⁷²As, ⁷⁵Br, ⁷⁶Br, ^(82m)Rb, ⁸³Sr, or other gamma-, beta-, or positron-emitters. Paramagnetic ions of use may include chromium (III), manganese (II), iron (III), iron (II), cobalt (II), nickel (II), copper (II), neodymium (III), samarium (III), ytterbium (III), gadolinium (III), vanadium (II), terbium (III), dysprosium (III), holmium (III) or erbium (III). Metal contrast agents may include lanthanum (III), gold (III), lead (II) or bismuth (III). Ultrasound contrast agents may comprise liposomes, such as gas filled liposomes. Radiopaque diagnostic agents may be selected from compounds, barium compounds, gallium compounds, and thallium compounds. A wide variety of fluorescent labels are known in the art, including but not limited to fluorescein isothiocyanate, rhodamine, phycoerytherin, phycocyanin, allophycocyanin, o-phthaldehyde and fluorescamine. Chemiluminescent labels of use may include luminol, isoluminol, an aromatic acridinium ester, an imidazole, an acridinium salt or an oxalate ester.

Conjugation Techniques

In certain embodiments, the cytokine-PEG DNL construct may be conjugated to one or more therapeutic or diagnostic agents. For example, ¹³¹I can be incorporated into a tyrosine of a protein or peptide, or a drug attached to an epsilon amino group of a lysine residue. Therapeutic and diagnostic agents also can be attached, for example to reduced SH groups. Many methods for making covalent or non-covalent conjugates of therapeutic or diagnostic agents with proteins or peptides are known in the art and any such known method may be utilized.

A therapeutic or diagnostic agent can be attached using a heterobifunctional cross-linker, such as N-succinyl 3-(2-pyridyldithio)propionate (SPDP). Yu et al., Int. J. Cancer 56: 244 (1994). General techniques for such conjugation are well-known in the art. See, for example, Wong, CHEMISTRY OF PROTEIN CONJUGATION AND CROSS-LINKING (CRC Press 1991); Upeslacis et al., “Modification of Antibodies by Chemical Methods,” in MONOCLONAL ANTIBODIES: PRINCIPLES AND APPLICATIONS, Birch et al. (eds.), pages 187-230 (Wiley-Liss, Inc. 1995); Price, “Production and Characterization of Synthetic Peptide-Derived Antibodies,” in MONOCLONAL ANTIBODIES: PRODUCTION, ENGINEERING AND CLINICAL APPLICATION, Ritter et al. (eds.), pages 60-84 (Cambridge University Press 1995).

In some embodiments, a chelating agent may be attached to a protein or peptide and used to chelate a therapeutic or diagnostic agent, such as a radionuclide. Exemplary chelators include but are not limited to DIVA (such as Mx-DTPA), DOTA, TETA, NETA or NOTA. Methods of conjugation and use of chelating agents to attach metals or other ligands to proteins or peptides are well known in the art (see, e.g., U.S. Pat. No. 7,563,433, the Examples section of which is incorporated herein by reference). Particularly useful metal-chelate combinations include 2-benzyl-DTPA and its monomethyl and cyclohexyl analogs, used with diagnostic isotopes in the general energy range of 60 to 4,000 keV, such as ¹²⁵I, ¹³¹I, ¹²³I, ¹²⁴I, ⁶²Cu, ⁶⁴Cu, ¹⁸F, ¹¹¹In, ⁶⁷Ga, ⁶⁸Ga, ^(99m)Tc, ^(94m)Tc, ¹¹C, ¹³N, ¹⁵O or ⁷⁶Br for radioimaging. The same chelates, when complexed with non-radioactive metals, such as manganese, iron and gadolinium are useful for MRI. Macrocyclic chelates such as NOTA, DOTA, and TETA are of use with a variety of metals and radiometals, most particularly with radionuclides of gallium, yttrium and copper, respectively. Such metal-chelate complexes can be made very stable by tailoring the ring size to the metal of interest. Other ring-type chelates such as macrocyclic polyethers, which are of interest for stably binding nuclides, such as ²²³Ra for RAIT are encompassed.

More recently, methods of ¹⁸F-labeling of use in PET scanning techniques have been disclosed, for example by reaction of F-18 with a metal or other atom, such as aluminum. The ¹⁸F—Al conjugate may be complexed with chelating groups, such as DOTA, NOTA or NETA that are attached directly to antibodies or used to label targetable constructs in pre-targeting methods. Such F-18 labeling techniques are disclosed in U.S. Pat. No. 7,563,433.

Methods of Therapeutic Treatment

Various embodiments concern methods of treating a cancer in a subject, such as a mammal, including humans, domestic or companion pets, such as dogs and cats, comprising administering to the subject a therapeutically effective amount of a cytokine-PEG DNL construct. The administration of cytokine-PEG DNL construct can be supplemented by administering concurrently or sequentially a therapeutically effective amount of an antibody that binds to or is reactive with an antigen on the surface of the target cell. Preferred additional MAbs comprise at least one humanized, chimeric or human MAb selected from the group consisting of a MAb reactive with CD4, CD5, CD8, CD14, CD15, CD16, CD19, IGF-1R, CD20, CD21, CD22, CD23, CD25, CD30, CD32b, CD33, CD37, CD38, CD40, CD40L, CD45, CD46, CD52, CD54, CD70, CD74, CD79a, CD80, CD95, CD126, CD133, CD138, CD154, CEACAM5, CEACAM6, B7, AFP, PSMA, EGP-1, EGP-2, carbonic anhydrase IX, PAM4 antigen, MUC1, MUC2, MUC3, MUC4, MUC5, Ia, MIF, HM1.24, HLA-DR, tenascin, Flt-3, VEGFR, P1GF, ILGF, IL-6, IL-25, tenascin, TRAIL-R1, TRAIL-R2, complement factor C5, oncogene product, or a combination thereof.

The cytokine-PEG DNL construct therapy can be further supplemented with the administration, either concurrently or sequentially, of at least one therapeutic agent. For example, “CVB” (1.5 g/m² cyclophosphamide, 200-400 mg/m² etoposide, and 150-200 mg/m² carmustine) is a regimen used to treat non-Hodgkin's lymphoma. Patti et al., Eur. J. Haematol. 51: 18 (1993). Other suitable combination chemotherapeutic regimens are well-known to those of skill in the art. See, for example, Freedman et al., “Non-Hodgkin's Lymphomas,” in CANCER MEDICINE, VOLUME 2, 3rd Edition, Holland et al. (eds.), pages 2028-2068 (Lea & Febiger 1993). As an illustration, first generation chemotherapeutic regimens for treatment of intermediate-grade non-Hodgkin's lymphoma (NHL) include C-MOPP (cyclophosphamide, vincristine, procarbazine and prednisone) and CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone). A useful second generation chemotherapeutic regimen is m-BACOD (methotrexate, bleomycin, doxorubicin, cyclophosphamide, vincristine, dexamethasone and leucovorin), while a suitable third generation regimen is MACOP-B (methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin and leucovorin). Additional useful drugs include phenyl butyrate, bendamustine, and bryostatin-1.

The cytokine-PEG DNL construct can be formulated according to known methods to prepare pharmaceutically useful compositions, whereby the cytokine-PEG DNL construct is combined in a mixture with a pharmaceutically suitable excipient. Sterile phosphate-buffered saline is one example of a pharmaceutically suitable excipient. Other suitable excipients are well-known to those in the art. See, for example, Ansel et al., PHARMACEUTICAL DOSAGE FORMS AND DRUG DELIVERY SYSTEMS, 5th Edition (Lea & Febiger 1990), and Gennaro (ed.), REMINGTON′S PHARMACEUTICAL SCIENCES, 18th Edition (Mack Publishing Company 1990), and revised editions thereof.

The cytokine-PEG DNL construct can be formulated for intravenous administration via, for example, bolus injection or continuous infusion. Preferably, cytokine-PEG DNL construct is infused over a period of less than about 4 hours, and more preferably, over a period of less than about 3 hours. For example, the first 25-50 mg could be infused within 30 minutes, preferably even 15 min, and the remainder infused over the next 2-3 hrs. Formulations for injection can be presented in unit dosage form, e.g., in ampoules or in multi-dose containers, with an added preservative. The compositions can take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and can contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredient can be in powder form for constitution with a suitable vehicle, e.g., sterile pyrogen-free water, before use.

Additional pharmaceutical methods may be employed to control the duration of action of the cytokine-PEG DNL construct. Control release preparations can be prepared through the use of polymers to complex or adsorb the cytokine-PEG DNL construct. For example, biocompatible polymers include matrices of poly(ethylene-co-vinyl acetate) and matrices of a polyanhydride copolymer of a stearic acid dimer and sebacic acid. Sherwood et al., Bio/Technology 10: 1446 (1992). The rate of release from such a matrix depends upon the molecular weight of the cytokine-PEG DNL construct, the amount of cytokine-PEG DNL construct within the matrix, and the size of dispersed particles. Saltzman et al., Biophys. J. 55: 163 (1989); Sherwood et al., supra. Other solid dosage forms are described in Ansel et al., PHARMACEUTICAL DOSAGE FORMS AND DRUG DELIVERY SYSTEMS, 5th Edition (Lea & Febiger 1990), and Gennaro (ed.), REMINGTON'S PHARMACEUTICAL SCIENCES, 18th Edition (Mack Publishing Company 1990), and revised editions thereof.

The cytokine-PEG DNL construct may also be administered to a mammal subcutaneously or even by other parenteral routes. Moreover, the administration may be by continuous infusion or by single or multiple boluses. Preferably, the cytokine-PEG DNL construct is infused over a period of less than about 4 hours, and more preferably, over a period of less than about 3 hours.

More generally, the dosage of an administered cytokine-PEG DNL construct for humans will vary depending upon such factors as the patient's age, weight, height, sex, general medical condition and previous medical history. The dosage may be repeated as needed, for example, once per week for 4-10 weeks, once per week for 8 weeks, or once per week for 4 weeks. It may also be given less frequently, such as every other week for several months, or monthly or quarterly for many months, as needed in a maintenance therapy. Alternatively, a cytokine-PEG DNL construct may be administered as one dosage every 2 or 3 weeks, repeated for a total of at least 3 dosages. Or, the construct may be administered twice per week for 4-6 weeks. The dosing schedule can optionally be repeated at other intervals and dosage may be given through various parenteral routes, with appropriate adjustment of the dose and schedule.

In preferred embodiments, the cytokine-PEG DNL constructs are of use for therapy of cancer. Examples of cancers include, but are not limited to, carcinoma, lymphoma, glioblastoma, melanoma, sarcoma, and leukemia, myeloma, or lymphoid malignancies. More particular examples of such cancers are noted below and include: squamous cell cancer (e.g., epithelial squamous cell cancer), Ewing sarcoma, Wilms tumor, astrocytomas, lung cancer including small-cell lung cancer, non-small cell lung cancer, adenocarcinoma of the lung and squamous carcinoma of the lung, cancer of the peritoneum, hepatocellular cancer, gastric or stomach cancer including gastrointestinal cancer, pancreatic cancer, glioblastoma multiforme, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma, hepatocellular carcinoma, neuroendocrine tumors, medullary thyroid cancer, differentiated thyroid carcinoma, breast cancer, ovarian cancer, colon cancer, rectal cancer, endometrial cancer or uterine carcinoma, salivary gland carcinoma, kidney or renal cancer, prostate cancer, vulvar cancer, anal carcinoma, penile carcinoma, as well as head-and-neck cancer. The term “cancer” includes primary malignant cells or tumors (e.g., those whose cells have not migrated to sites in the subject's body other than the site of the original malignancy or tumor) and secondary malignant cells or tumors (e.g., those arising from metastasis, the migration of malignant cells or tumor cells to secondary sites that are different from the site of the original tumor).

Other examples of cancers or malignancies include, but are not limited to: Acute Childhood Lymphoblastic Leukemia, Acute Lymphoblastic Leukemia, Acute Lymphocytic Leukemia, Acute Myeloid Leukemia, Adrenocortical Carcinoma, Adult (Primary) Hepatocellular Cancer, Adult (Primary) Liver Cancer, Adult Acute Lymphocytic Leukemia, Adult Acute Myeloid Leukemia, Adult Hodgkin's Lymphoma, Adult Lymphocytic Leukemia, Adult Non-Hodgkin's Lymphoma, Adult Primary Liver Cancer, Adult Soft Tissue Sarcoma, AIDS-Related Lymphoma, AIDS-Related Malignancies, Anal Cancer, Astrocytoma, Bile Duct Cancer, Bladder Cancer, Bone Cancer, Brain Stem Glioma, Brain Tumors, Breast Cancer, Cancer of the Renal Pelvis and Ureter, Central Nervous System (Primary) Lymphoma, Central Nervous System Lymphoma, Cerebellar Astrocytoma, Cerebral Astrocytoma, Cervical Cancer, Childhood (Primary) Hepatocellular Cancer, Childhood (Primary) Liver Cancer, Childhood Acute Lymphoblastic Leukemia, Childhood Acute Myeloid Leukemia, Childhood Brain Stem Glioma, Childhood Cerebellar Astrocytoma, Childhood Cerebral Astrocytoma, Childhood Extracranial Germ Cell Tumors, Childhood Hodgkin's Disease, Childhood Hodgkin's Lymphoma, Childhood Hypothalamic and Visual Pathway Glioma, Childhood Lymphoblastic Leukemia, Childhood Medulloblastoma, Childhood Non-Hodgkin's Lymphoma, Childhood Pineal and Supratentorial Primitive Neuroectodermal Tumors, Childhood Primary Liver Cancer, Childhood Rhabdomyosarcoma, Childhood Soft Tissue Sarcoma, Childhood Visual Pathway and Hypothalamic Glioma, Chronic Lymphocytic Leukemia, Chronic Myelogenous Leukemia, Colon Cancer, Cutaneous T-Cell Lymphoma, Endocrine Pancreas Islet Cell Carcinoma, Endometrial Cancer, Ependymoma, Epithelial Cancer, Esophageal Cancer, Ewing's Sarcoma and Related Tumors, Exocrine Pancreatic Cancer, Extracranial Germ Cell Tumor, Extragonadal Germ Cell Tumor, Extrahepatic Bile Duct Cancer, Eye Cancer, Female Breast Cancer, Gaucher's Disease, Gallbladder Cancer, Gastric Cancer, Gastrointestinal Carcinoid Tumor, Gastrointestinal Tumors, Germ Cell Tumors, Gestational Trophoblastic Tumor, Hairy Cell Leukemia, Head and Neck Cancer, Hepatocellular Cancer, Hodgkin's Lymphoma, Hypergammaglobulinemia, Hypopharyngeal Cancer, Intestinal Cancers, Intraocular Melanoma, Islet Cell Carcinoma, Islet Cell Pancreatic Cancer, Kaposi's Sarcoma, Kidney Cancer, Laryngeal Cancer, Lip and Oral Cavity Cancer, Liver Cancer, Lung Cancer, Lymphoproliferative Disorders, Macroglobulinemia, Male Breast Cancer, Malignant Mesothelioma, Malignant Thymoma, Medulloblastoma, Melanoma, Mesothelioma, Metastatic Occult Primary Squamous Neck Cancer, Metastatic Primary Squamous Neck Cancer, Metastatic Squamous Neck Cancer, Multiple Myeloma, Multiple Myeloma/Plasma Cell Neoplasm, Myelodysplastic Syndrome, Myelogenous Leukemia, Myeloid Leukemia, Myeloproliferative Disorders, Nasal Cavity and Paranasal Sinus Cancer, Nasopharyngeal Cancer, Neuroblastoma, Non-Hodgkin's Lymphoma, Nonmelanoma Skin Cancer, Non-Small Cell Lung Cancer, Occult Primary Metastatic Squamous Neck Cancer, Oropharyngeal Cancer, Osteo-/Malignant Fibrous Sarcoma, Osteosarcoma/Malignant Fibrous Histiocytoma, Osteosarcoma/Malignant Fibrous Histiocytoma of Bone, Ovarian Epithelial Cancer, Ovarian Germ Cell Tumor, Ovarian Low Malignant Potential Tumor, Pancreatic Cancer, Paraproteinemias, Polycythemia vera, Parathyroid Cancer, Penile Cancer, Pheochromocytoma, Pituitary Tumor, Primary Central Nervous System Lymphoma, Primary Liver Cancer, Prostate Cancer, Rectal Cancer, Renal Cell Cancer, Renal Pelvis and Ureter Cancer, Retinoblastoma, Rhabdomyosarcoma, Salivary Gland Cancer, Sarcoidosis Sarcomas, Sezary Syndrome, Skin Cancer, Small Cell Lung Cancer, Small Intestine Cancer, Soft Tissue Sarcoma, Squamous Neck Cancer, Stomach Cancer, Supratentorial Primitive Neuroectodermal and Pineal Tumors, T-Cell Lymphoma, Testicular Cancer, Thymoma, Thyroid Cancer, Transitional Cell Cancer of the Renal Pelvis and Ureter, Transitional Renal Pelvis and Ureter Cancer, Trophoblastic Tumors, Ureter and Renal Pelvis Cell Cancer, Urethral Cancer, Uterine Cancer, Uterine Sarcoma, Vaginal Cancer, Visual Pathway and Hypothalamic Glioma, Vulvar Cancer, Waldenstrom's Macroglobulinemia, Wilms' Tumor, and any other hyperproliferative disease, besides neoplasia, located in an organ system listed above.

The methods and compositions described and claimed herein may be used to treat malignant or premalignant conditions and to prevent progression to a neoplastic or malignant state, including but not limited to those disorders described above. Such uses are indicated in conditions known or suspected of preceding progression to neoplasia or cancer, in particular, where non-neoplastic cell growth consisting of hyperplasia, metaplasia, or most particularly, dysplasia has occurred (for review of such abnormal growth conditions, see Robbins and Angell, Basic Pathology, 2d Ed., W. B. Saunders Co., Philadelphia, pp. 68-79 (1976)).

Dysplasia is frequently a forerunner of cancer, and is found mainly in the epithelia. It is the most disorderly form of non-neoplastic cell growth, involving a loss in individual cell uniformity and in the architectural orientation of cells. Dysplasia characteristically occurs where there exists chronic irritation or inflammation. Dysplastic disorders which can be treated include, but are not limited to, anhidrotic ectodermal dysplasia, anterofacial dysplasia, asphyxiating thoracic dysplasia, atriodigital dysplasia, bronchopulmonary dysplasia, cerebral dysplasia, cervical dysplasia, chondroectodermal dysplasia, cleidocranial dysplasia, congenital ectodermal dysplasia, craniodiaphysial dysplasia, craniocarpotarsal dysplasia, craniometaphysial dysplasia, dentin dysplasia, diaphysial dysplasia, ectodermal dysplasia, enamel dysplasia, encephalo-ophthalmic dysplasia, dysplasia epiphysialis hemimelia, dysplasia epiphysialis multiplex, dysplasia epiphysialis punctata, epithelial dysplasia, faciodigitogenital dysplasia, familial fibrous dysplasia of jaws, familial white folded dysplasia, fibromuscular dysplasia, fibrous dysplasia of bone, florid osseous dysplasia, hereditary renal-retinal dysplasia, hidrotic ectodermal dysplasia, hypohidrotic ectodermal dysplasia, lymphopenic thymic dysplasia, mammary dysplasia, mandibulofacial dysplasia, metaphysial dysplasia, Mondini dysplasia, monostotic fibrous dysplasia, mucoepithelial dysplasia, multiple epiphysial dysplasia, oculoauriculovertebral dysplasia, oculodentodigital dysplasia, oculovertebral dysplasia, odontogenic dysplasia, opthalmomandibulomelic dysplasia, periapical cemental dysplasia, polyostotic fibrous dysplasia, pseudoachondroplastic spondyloepiphysial dysplasia, retinal dysplasia, septo-optic dysplasia, spondyloepiphysial dysplasia, and ventriculoradial dysplasia.

Additional pre-neoplastic disorders which can be treated include, but are not limited to, benign dysproliferative disorders (e.g., benign tumors, fibrocystic conditions, tissue hypertrophy, intestinal polyps or adenomas, and esophageal dysplasia), leukoplakia, keratoses, Bowen's disease, Farmer's Skin, solar cheilitis, and solar keratosis.

In preferred embodiments, the method of the invention is used to inhibit growth, progression, and/or metastasis of cancers, in particular those listed above.

Additional hyperproliferative diseases, disorders, and/or conditions include, but are not limited to, progression, and/or metastases of malignancies and related disorders such as leukemia (including acute leukemias (e.g., acute lymphocytic leukemia, acute myelocytic leukemia (including myeloblastic, promyelocytic, myelomonocytic, monocytic, and erythroleukemia)) and chronic leukemias (e.g., chronic myelocytic (granulocytic) leukemia and chronic lymphocytic leukemia)), polycythemia vera, lymphomas (e.g., Hodgkin's disease and non-Hodgkin's disease), multiple myeloma, Waldenstrom's macroglobulinemia, heavy chain disease, and solid tumors including, but not limited to, sarcomas and carcinomas such as fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenic sarcoma, chordoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma, lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's tumor, leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, pancreatic cancer, breast cancer, ovarian cancer, prostate cancer, squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinomas, cystadenocarcinoma, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma, bile duct carcinoma, choriocarcinoma, seminoma, embryonal carcinoma, Wilm's tumor, cervical cancer, testicular tumor, lung carcinoma, small cell lung carcinoma, bladder carcinoma, epithelial carcinoma, glioma, astrocytoma, medulloblastoma, craniopharyngioma, ependymoma, pinealoma, emangioblastoma, acoustic neuroma, oligodendroglioma, meningioma, melanoma, neuroblastoma, and retinoblastoma.

In still other embodiments, the PEGylated DNL complexes may be of use to treat subjects infected with pathogenic organisms, such as bacteria, viruses or fungi. Exemplary fungi that may be treated include Microsporum, Trichophyton, Epidermophyton, Sporothrix schenckii, Cryptococcus neoformans, Coccidioides immitis, Histoplasma capsulatum, Blastomyces dermatitidis or Candida albicans. Exemplary viruses include human immunodeficiency virus (HIV), herpes virus, cytomegalovirus, rabies virus, influenza virus, human papilloma virus, hepatitis B virus, hepatitis C virus, Sendai virus, feline leukemia virus, Reo virus, polio virus, human serum parvo-like virus, simian virus 40, respiratory syncytial virus, mouse mammary tumor virus, Varicella-Zoster virus, Dengue virus, rubella virus, measles virus, adenovirus, human T-cell leukemia viruses, Epstein-Barr virus, murine leukemia virus, mumps virus, vesicular stomatitis virus, Sindbis virus, lymphocytic choriomeningitis virus or blue tongue virus. Exemplary bacteria include Bacillus anthracis, Streptococcus agalactiae, Legionella pneumophila, Streptococcus pyogenes, Escherichia coli, Neisseria gonorrhoeae, Neisseria meningitidis, Pneumococcus spp., Hemophilus influenzae B, Treponema pallidum, Lyme disease spirochetes, Pseudomonas aeruginosa, Mycobacterium leprae, Brucella abortus, Mycobacterium tuberculosis or a Mycoplasma.

Kits

Various embodiments may concern kits containing components suitable for treating diseased tissue in a patient. Exemplary kits may contain at least one or more cytokine-PEG constructs as described herein. If the composition containing components for administration is not formulated for delivery via the alimentary canal, such as by oral delivery, a device capable of delivering the kit components through some other route may be included. One type of device, for applications such as parenteral delivery, is a syringe that is used to inject the composition into the body of a subject. Inhalation devices may also be used. In certain embodiments, a therapeutic agent may be provided in the form of a prefilled syringe or autoinjection pen containing a sterile, liquid formulation or lyophilized preparation.

The kit components may be packaged together or separated into two or more containers. In some embodiments, the containers may be vials that contain sterile, lyophilized formulations of a composition that are suitable for reconstitution. A kit may also contain one or more buffers suitable for reconstitution and/or dilution of other reagents. Other containers that may be used include, but are not limited to, a pouch, tray, box, tube, or the like. Kit components may be packaged and maintained sterilely within the containers. Another component that can be included is instructions to a person using a kit for its use.

EXAMPLES

The following examples are provided to illustrate, but not to limit, the claims of the present invention.

Example 1 Generation of PEG-AD2 Modules

Synthesis of IMP350 (SEQ ID NO: 21) CGQIEYLAKQIVDNAIQQAGC(SS-tbu)-NH₂ MH⁺2354

IMP350 was made on a 0.1 mmol scale with Sieber Amide resin using Fmoc methodology on a Protein Technologies PS3 peptide synthesizer. Starting from the C-terminus the protected amino acids used were Fmoc-Cys(t-Buthio)-OH, Fmoc-Gly-OH, Fmoc-Ala-OH, Fmoc-Gln(Trt)-OH, Fmoc-Gln(Trt)-OH, Fmoc-Ile-OH, Fmoc-Ala-OH, Fmoc-Asn(Trt)-OH, Fmoc-Asp(OBut)-OH, Fmoc-Val-OH, Fmoc-Ile-OH, Fmoc-Gln(Trt)-OH, Fmoc-Lys(Boc)-OH, Fmoc-Ala-OH, Fmoc-Leu-OH, Fmoc-Tyr(But)-OH, Fmoc-Glu(OBut)-OH, Fmoc-Ile-OH, Fmoc-Gln(Trt)-OH, Fmoc-Gly-OH and Fmoc-Cys(Trt)-OH. The peptide was cleaved from the resin and purified by reverse phase (RP)-HPLC.

Synthesis of PEG₂₀-IMP350

IMP350 (0.0104 g) was mixed with 0.1022 g of mPEG-OPTE (20 kDa, Nektar Therapeutics) in 7 mL of 1 M Tris buffer at pH 7.81. Acetonitrile, 1 mL, was then added to dissolve some suspended material. The reaction was stirred at room temperature for 3 h and then 0.0527 g of TCEP was added along with 0.0549 g of cysteine. The reaction mixture was stirred for 1.5 h and then purified on a PD-10 desalting column, which was equilibrated with 20% methanol in water. The sample was eluted, frozen and lyophilized to obtain 0.0924 g of crude PEG₂₀-IMP350 (MH+23508 by MALDI).

Synthesis of IMP360

(SEQ ID NO: 22) CGQIEYLAKQIVDNAIQQAGC(SS-tbu)-G-EDANS MH⁺2660

IMP 360 was synthesized on a 0.1 mmol scale with EDANS resin (Nova Biochem) using Fmoc methodology on a Protein Technologies PS3 peptide synthesizer. Starting from the C-terminus the protected amino acids used were Fmoc-Cys(t-Buthio)-OH, Fmoc-Gly-OH, Fmoc-Ala-OH, Fmoc-Gln(Trt)-OH, Fmoc-Gln(Trt)-OH, Fmoc-Ile-OH, Fmoc-Ala-OH, Fmoc-Asn(Trt)-OH, Fmoc-Asp(OBut)-OH, Fmoc-Val-OH, Fmoc-Ile-OH, Fmoc-Gln(Trt)-OH, Fmoc-Lys(Boc)-OH, Fmoc-Ala-OH, Fmoc-Leu-OH, Fmoc-Tyr(But)-OH, Fmoc-Glu(OBut)-OH, Fmoc-Ile-OH, Fmoc-Gln(Trt)-OH, Fmoc-Gly-OH and Fmoc-Cys(Trt)-OH. The peptide was cleaved from the resin and purified by RP-HPLC, and determined to have a molecular mass of 2,660 Da.

Generation of IMP362 and IMP413

The two linear PEG-AD2 modules were prepared by coupling IMP360 to mPEG-OPTE (Nectar Therapeutics, San Carlos, Calif.) of 20-kDa or 30-kDa, resulting in IMP362 or IMP413, respectively. To prepare IMP362, IMP360 (11.5 mg) was mixed with 20-kDa mPEG-OPTE (127 mg) in 7 mL of 1 M Tris-HCL, pH 7.8. Acetonitrile (1 mL) was added to dissolve some suspended material. The reaction was stirred at room temperature for 4 h to effect the attachment of mPEG to the amino-terminal cysteine via an amide bond. Subsequently, 41 mg of Tris [2-carboxyethyl] phosphine hydrochloride (TCEP) and 43 mg of cysteine were added to de-protect the remaining cysteine. The reaction mixtures were stirred for 1 h and desalted using PD-10 columns, which had been equilibrated with 20% methanol in water. The samples were lyophilized to obtain approximately 150 mg of IMP362 (MH+23713). IMP413 (MH⁺34499) was made similarly using 30-kDa mPEG-OPTE (190 mg).

Generation of IMP421 and IMP457

The AD2-containing peptide (IMP421, MH⁺2891, FIG. 1A) was made for derivatizing mPEG2-MAL-40K (Nectar Therapeutics) to obtain the branched PEG-AD2 module (IMP457). IMP421 was synthesized on NovaSyn® TGR resin (487.6 mg, 0.112 mmol) by adding the following amino acids to the resin in the order shown: Fmoc-Gly-OH, Fmoc-Cys(t-Buthio)-OH, Fmoc-Gly-OH, Fmoc-Ala-OH, Fmoc-Gln(Trt)-OH, Fmoc-Gln(Trt)-OH, Fmoc-Ile-OH, Fmoc-Ala-OH, Fmoc-Asn(Trt)-OH, Fmoc-Asp(OBut)-OH, Fmoc-Val-OH, Fmoc-Ile-OH, Fmoc-Gln(Trt)-OH, Fmoc-Lys(Boc)-OH, Fmoc-Ala-OH, Fmoc-Leu-OH, Fmoc-Tyr(But)-OH, Fmoc-Glu(OBut)-OH, Fmoc-Ile-OH, Fmoc-Gln(Trt)-OH, Fmoc-Gly-OH, Fmoc-Cys(t-Buthio)-OH, Fmoc-NH-PEG₃-COOH, Fmoc-Cys(Trt)-OH. The N-terminal amino acid was protected as an acetyl derivative. The peptide was then cleaved from the resin and purified by RP-HPLC to yield 32.7 mg of a white solid.

IMP457 was made as follows. To a solution of IMP421 (15.2 mg, 5.26 mop and mPEG2-MAL-40K (274.5 mg, 6.86 mop in 1 mL of acetonitrile was added 7 mL of 1 M Tris pH 7.8. After 3 h at room temperature, the excess mPEG2-MAL-40K was quenched with L-cysteine (49.4 mg), followed by S-S-tBu deprotection over 1 h with TCEP (59.1 mg). The resulting solution was dispensed into two 10K Slide-A-Lyzer dialysis cassettes (4 mL in each) and dialyzed overnight at 2-8° C. against 5 L of 5 mM Ammonium Acetate, pH 5.0. Following three additional 5-L buffer changes, the dialyzed solution (19.4 mL) was transferred into two 20-mL scintillation vials, frozen and lyophilized to yield a white solid (246.7 mg). The molecular mass as determined by MALDI-TOF was 42,982 for mPEG2-MAL-40K and 45,500 for IMP457.

Example 2 Generation of DDD Module Based on Interferon (IFN)-α2b

Construction of IFN-α2b-DDD2-pdHL2 for Expression in Mammalian Cells

The cDNA sequence for IFN-α2b was amplified by PCR, resulting in a sequence comprising the following features, in which XbaI and BamHI are restriction sites, the signal peptide is native to IFN-α2b, and 6 His is a hexahistidine tag: XbaI—Signal peptide—IFNα2b—6 His—BamHI (6 His is disclosed as SEQ ID NO: 30). The resulting secreted protein will consist of IFN-α2b fused at its C-terminus to a polypeptide consisting of SEQ ID NO:23.

(SEQ ID NO: 23) KSHHHHHHGSGGGGSGGGCGHIQIPPGLTELLQGYTVEVLRQQPPDLVEFAVEYFTRLREARA 

PCR amplification was accomplished using a full length human IFNα2b cDNA clone (Invitrogen Ultimate ORF human clone cat#HORF01Clone ID 10H35221) as a template and the following oligonucleotides as primers:

IFNA2 Xba I Left (SEQ ID NO: 24) 5′-TCTAGACACAGGACCTCATCATGGCCTTGACCTTTGCTTTACTGG-3′ IFNA2 BamHI right (SEQ ID NO: 25) 5′-GGATCCATGATGGTGATGATGGTGTGACTTTTCCTTACTTCTTAAACTTTCTTGC-3′

The PCR amplimer was cloned into the pGemT vector (Promega). A DDD2-pdHL2 mammalian expression vector was prepared for ligation with IFN-α2b by digestion with XbaI and Bam HI restriction endonucleases. The IFN-α2b amplimer was excised from pGemT with XbaI and Bam HI and ligated into the DDD2-pdHL2 vector to generate the expression vector IFN-α2b-DDD2-pdHL2.

Mammalian Expression of IFN-α2b-DDD2

IFNα2b-DDD2-pdHL2 (30 μg) was linearized by digestion with SalI and stably transfected by electroporation (450 volts, 25 μF) into Sp/ESF myeloma cells (2.8×10⁶ cells), an engineered derivative of Sp2/0 that can be grown and transfected in serum-free medium. Transfectants were cultured in Hybridoma SFM (Invitrogen, Carlsbad Calif.) supplemented with 0.2 μM methotrexate (Calbiochem, LaJolla, Calif.) in 96-well plates, and screened for IFN-α2b expression with a human interferon alpha ELISA kit (PBL Interferon Source, Piscataway, N.J.) following the manufacturers' instructions.

Purification of IFN-α2b-DDD2 from Batch Cultures Grown in Roller Bottles

Briefly, the supernatant fluid was clarified by centrifugation, filtered through 0.2 micron membranes, diafiltered into 1× binding buffer (10 mM imidazole, 0.5 M NaCl, 50 mM NaH₂PO₄, pH 7.5), concentrated 20-fold, and loaded onto a Ni-NTA column (Qiagen). After washing with 0.02% Tween 20 in 1× binding buffer and then 30 mM imidazole, 0.02% Tween 20, 0.5 M NaCl, 50 mM NaH₂PO₄, pH 7.5, α2b-DDD2 was eluted with 250 mM imidazole, 0.02% Tween 20, 150 mM NaCl, 50 mM NaH₂PO₄, pH 7.5, and stored in the same buffer at 2-8° C. until needed. The monomeric form of α2b-DDD2 consists of IFN-α2b fused at its carboxyl-terminus to a 63-residue peptide of SEQ ID NO:23.

Example 3 Preparation and Purification of α2b-362, α2b-413 and α2b-457

Conjugations of α2b-DDD2 with IMP362, IMP413, and IMP457 were performed to generate PEGylated α2b-362, α2b-413, and α2b-457, respectively. In general, a 10-fold molar excess of reduced and lyophilized IMP362, IMP413, or IMP457 (about 11 mg each) was added to 2.25 mg of α2b-DDD2 in 3.5 mL of 250 mM imidazole, 0.02% Tween 20, 150 mM NaCl, 1 mM EDTA, 50 mM NaH₂PO₄, pH 7.5. After 6 h at room temperature in the dark, the reaction mixture was dialyzed against CM loading buffer (150 mM NaCl, 20 mM NaAc, pH 4.5) at 4° C. in the dark. The PEGylated product was purified by cation exchange chromatography using a 1-mL Hi-Trap CM-FF column (Amersham), which was equilibrated with CM loading buffer. After sample loading, the column was washed with CM loading buffer to baseline, followed by washing with 15 mL of 0.25 M NaCl, 20 mM NaAc, pH 4.5. The PEGylated product was eluted with 12.5 mL of 0.5 M NaCl, 20 mM NaAc, pH 4.5.

SDS-PAGE, Fluorescence Imaging, and Immunoblot

Reducing and non-reducing SDS-PAGE analyses were performed using 4-20% gradient Tris-Glycine gels (Cambrex Bio Science Rockland, Rockland, Me.). To normalize the samples for direct protein mass comparison, each fraction eluted from the CM-FF column was concentrated to 3.5 mL to match the reaction volume. Samples were diluted with an equal volume of 2× sample buffer (2% SDS, 5% glycerol, 62.5 mM Tris-HCl, pH 6.8) and heated to 95° C. before was loading 10 μL per lane. For reducing gels, 5% of β-2-mercaptoethanol was included in the sample buffer. Gels were imaged by direct fluorescence to visualize bands containing the EDANS tag using a Kodak Image Station 4000R before staining with Coomassie blue to visualize the protein bands. Duplicate gels were transferred to PVDF membranes for immunoblot analysis. Blots were probed with rabbit anti-interferon alpha polyclonal antibody (AB1434, Chemicon International) diluted 1:1,000 in 1% BSA-PBST. Signal was detected with HRP-conjugated goat anti-rabbit IgG (Jackson Immunoresearch) and ECL (Pierce).

Characterization of α2b-362 and α2b-413

We produced a DDD2 module of IFN-α2b with a hexa-histidine tag (SEQ ID NO: 30) in myeloma cells, and synthesized two AD2 modules of linear PEG, one with a 20-kDa PEG, designated IMP362, and the other with a 30-kDa PEG, designated IMP413. In addition, each PEG-AD2 module also contained EDANS as a fluorescent tag. The fusion protein (IFNα2b-DDD2) was reacted with IMP362 and IMP413 in excess to yield the two PEGylated conjugates, α2b-362 and α2b-413, respectively, which were purified by cation exchange chromatography at pH 4.5.

The DNL process for generating α2b-362 was analyzed by non-reducing (NR) and reducing (R) SDS-PAGE with three visualization methods: Coomassie blue staining (FIG. 2A and FIG. 2D), fluorescence imaging (FIG. 2B and FIG. 2E) and immunoblotting (FIG. 2C). The Coomassie blue-stained gel shown in FIG. 2A revealed the presence of a major band of ˜110 kDa in the reaction mixture (lane 2, NR), which was absent in the unbound (lane 3, NR) or 0.25 M NaCl wash (lane 4, NR), but evident in the 0.5 M NaCl fraction (lane 5, NR).

Fluorescence imaging was used to detect the EDANS tag on IMP362 and the results shown in FIG. 2B indicate the presence of covalently attached IMP362 in the 110-kDa band (lanes 2 and 5, NR) as well as the presence of excess IMP362, which does not stain with Coomassie blue, in the reaction mixture (lane 2, NR and R) and the unbound fraction (lane 3, NR). Immunoblotting with anti-IFN-α confirmed the inclusion of IFN-α2b in the 110-kDa band (FIG. 2C, lanes 2 and 5, NR and R). The mass of α2b-326 was determined by MALDI-TOF to be 76,728 Da, which is consistent with a dimeric form of IFN-α2b-DDD2 (˜55 kDa) linked to one IMP362 (˜22 kDa). The observed discrepancy between the measured mass (˜77 kDa) by MALDI-TOF and the estimated molecular weight (˜110 kDa) by SDS-PAGE is due to PEG, which is known to increase the apparent molecular weight of PEGgylated products as determined by SDS-PAGE or SE-HPLC. In all reducing gels, the components of α2b-362 (lane 5) are dissociated into IMP362 and the monomeric form of α2b-DDD2, as expected. For α2b-413, which was generated and purified similarly, both Coomassie blue staining (FIG. 2D) and fluorescence imaging (FIG. 2E) show a major band of ˜125 kDa (lane 6, NR) migrating behind α2b-362 (lane 5, NR). Moreover, reducing SDS-PAGE showed only the presence of a single band corresponding to the monomeric form of α2b-DDD2 for both α2b-362 (lane 5, R) and α2b-413 (lane 6, R) by Coomassie blue staining, and the two distinct bands corresponding to IMP362 (FIG. 2E, lane 5, R) and IMP413 (FIG. 2E, lane 6, R) by fluorescence imaging. These results demonstrated that α2b-362 and α2b-413 were generated as designed and were substantially pure.

Example 4 Anti-Viral Effect of PEGylated IFN-α2b

The reduction of viral cytopathic effect (CPE) was determined by an independent laboratory (PBL Interferon Source, Piscataway, N.J.) using encephalomyocarditis virus (EMCV) and human lung epithelial A549 cells. Plates were stained with crystal violet and the OD was measured by spectrophotometry on a 96-well plate reader following solubilization of the dye. The data were analyzed with Graph Pad Prizm software (Advanced Graphics Software, Encinitas, Calif.) using a sigmoidal fit (variable slope) non-linear regression. The anti-viral titer was determined by comparison of EC₅₀ values with that of an IFNα standard.

The biological activities of α2b-362 and α2b-413 were compared with PEGINTRON® and PEGASYS® by measuring the cytopathic effect (CPE) of encephalomyocarditis virus (EMCV) on human lung epithelial A549 cells and the resulting EC₅₀ values were calculated to determine the anti-viral specific activities based on a validated IFN-α2b standard. As shown in FIG. 3A, on a molar basis, α2b-362, α2b-413, and PEGINTRON® all have similar specific activities (averaging 7×10¹² to 9×10¹² U/mmol) and are about 5-fold more potent than PEGASYS®. These data indicate that site-specific PEGylation by DNL may preserve biological activity better, particularly when using large PEG molecules. In addition, a cell-based kit, which utilizes a transgenic human pro-monocyte cell line carrying a reporter gene fused to an interferon-stimulated response element, was used to determine the specific activities of α2b-362 and α2b-413 to be 2940 IU/pmol and 816 IU/pmol, respectively, both of which were higher than PEGASYS® (170 IU/pmol) but lower than PEGINTRON® (3400 IU/pmol).

Example 5 In Vitro Anti-Proliferative Effect of PEGylated IFN-α2b in Cancer Cells

Each test compound was diluted to 500 pM in RPMI 1640 media supplemented with 10% FBS, from which triplicate, three-fold serial dilutions were made in 96-well tissue culture plates (50 μL sample/well). Daudi cells were diluted to 4×10⁵ cells/mL and 50 μL were added to each well (20K/well). After 4 days at 37° C., MTS was added to the plates (20 μL per well) and the plates were read after 3 to 4 h with an Envision plate reader (Perkin-Elmer, Boston Mass.) at 490 nm. Dose-response curves were generated and EC₅₀ values were obtained by sigmoidal fit non-linear regression using Graph Pad Prism software. Specific activities were determined by comparison of EC₅₀ values with PEGINTRON® using the specific activity provided with the product insert.

We compared the anti-proliferative activity of α2b-362 and α2b-413 with PEGINTRON® and PEGASYS® in Daudi lymphoma cells, with the finding (FIG. 3B) that α2b-362 and α2b-413 had 2-3-fold lower EC₅₀ values than PEGINTRON® (˜1×10¹² U/mmol vs. 2.2×10¹² U/mmol), but were comparable to PEGASYS®.

Example 6 Pharmacokinetics of PEGylated IFN-αab in Mice

The initial study evaluating α2b-362, α2b-413, PEGINTRON®, and rhIFN-α2a (Chemicon IF007, Lot 06008039084) was performed in 4 different groups of adult female Swiss-Webster mice (˜35 g) with 2 mice in each group. Each test compound was administered as a single bolus i.v. injection at a mole-equivalent dose: rhIFN-α2a, 3 μg; PEGINTRON®, 5 μg; α2b-362, 11 μg; and α2b-413, 13 μg. Mice were bled via the retro-orbital method at various time-points (pre-dose, 5-min, 2-, 8-, 24-, 48-, 72-, 96-, and 168-h post-injection).

The subsequent study evaluating α2b-457, α2b-413, PEGINTRON®, and PEGASYS® was performed in 4 different groups of adult male Swiss-Webster mice (˜40 g) with 4 in each group. Each test compound was administered as a single s.c. injection at a mole-equivalent dose (100 pmoles) in equal volumes (250 μL). Mice were bled via the retro-orbital method at various time-points (30-min, 2-, 8-, 24-, 48-, 72-, and 96-h post-injection). For each study, the blood was allowed to clot, centrifuged, and the serum removed for storage at −70° C. until analysis.

Concentrations of IFN-α in the serum samples were determined using a human interferon alpha ELISA kit (PBL Interferon Source) following the manufacturers' instructions. Briefly, the serum samples were diluted appropriately according to the human IFN-α standard provided in the kit. The antibody coupled to the microtiter plate wells captures interferon. A second antibody was then used to reveal the bound interferon, which was quantified by anti-secondary antibody conjugated to horseradish peroxidase (HRP) following the addition of tetramethyl benzidine (TMB) substrate. The plates were read at 450 nm. The amount of IFN in the serum for each animal was used to determine the various PK parameters. These data were analyzed with WinNonLin PK software (v5.1; Pharsight Corp.; Mountain View, Calif.) using non-compartmental analysis (representing the best-fit model for the data).

The pharmacokinetics (PK) of α2b-362 and α2b-413 in mice following a single i.v. injection were compared to those of PEGINTRON® and recombinant human IFN-α2b (rhIFN-α2b). The PK properties of each agent are summarized in Table 1 and the elimination curves are plotted in FIG. 4. As expected, rhIFN-α2b cleared most rapidly from the blood of injected mice, approximately 3-fold faster than PEGINTRON® and more than 13-fold faster than 2b-362 or 2b-413, either of which clears about 4-fold slower than PEGINTRON®, with little difference in the elimination rates between α2b-362 and α2b-413. As for mean residence time (MRT), a clear correlation with size is apparent among the various agents: the larger the molecular size, the longer the MRT. Finally, a test for bioequivalence showed that none of the agents tested were the same terms of PK.

TABLE 1 PK analysis of rhIFNα2b, PEGINTRON ®, α2b-362 and α2b-413 administered as intravenous injections to naïve Swiss-Webster mice. Ani- Elimi- mal Injected nation MRT Num- Dose C_(max) T_(1/2α) T_(1/2β) AUC_(0.08→∞) Rate _(0.08→∞) ber (pmoles) (pM) (hours) (hours) (h * pM) (1/h) (h) rhIFNα2b 1 160  16,411 0.29 10.53  7,011 2.34  0.63 2 160  21,835 0.31  7.14  10,147 2.15  0.78 Mean 160  19,123 0.30  8.84  8,579 2.25  0.71 PEG-INTRON 1 160  87,090 0.53  6.29 137,790 0.63  5.42 2 160 105,774 0.43  5.11 150,905 0.70  4.79 Mean 160  96,432 0.48  5.70 144,348 0.67  5.11 α2b-362 1 320  60,833 1.72  7.54 379,462 0.16  9.03 2 320  97,089 1.43 10.14 570,336 0.17 11.56 Mean 320  78,961 1.58  8.84 474,899 0.17 10.30 α2b-413 1 320 152,923 0.69 12.85 1,012,470  0.15 16.75 2 320 100,495 4.03 28.53 1,179,056  0.09 26.56 Mean 320 126,709 2.36 20.69 1,095,763  0.12 21.66

Example 7 In Vivo Anti-Tumor Efficacy of PEGylated IFN-α2b

Four studies were performed in eight-week-old female SCID mice injected i.v. with 1.5×10⁷ Daudi cells per animal. Therapy commenced 1 day after the Daudi transplantation. Mice were observed daily for signs of distress and paralysis and were weighed weekly. In the event a mouse lost greater than 15% of its body weight (but <20%) it was weighed every 2 days until it either gained back its weight to <15% loss or was sacrificed due to >20% loss. Mice were also terminated when hind-limb paralysis developed or if they became otherwise moribund.

For the first study there were 10 different treatment groups of 5 mice each. Equivalent units of activity of PEGINTRON®, α2b-362 and α2b-413 were administered once every 7 days via s.c. injection in either the left or right flank at three different doses (3,500, 7,000, and 14,000 IU). In the second study, 14,000 IU of PEGINTRON® or α2b-413 were administered s.c. with varied dosing schedules: once weekly for 4 weeks (q7dx4), once bi-weekly over 8 weeks (q2wk×4), and once tri-weekly over 12 weeks (q3wk×4). There were 7 different treatment groups of 6-7 mice each. All the mice received a total of 4 injections. The third study was performed in four treatment groups of 10 each, evaluating 14,000 IU of c2b-413 or PEGINTRON® given s.c. once every four weeks vs. once weekly. In the fourth study, α2b-457 was compared with α2b-413 and PEGINTRON® in two different doses (20 and 10 pmol) given four weeks apart.

In the initial study, PEGINTRON®, α2b-362 and α2b-413, at equivalent units of activity based on the in vitro growth inhibition assay, were each administered once weekly at three different doses (3,500, 7,000, and 14,000 U), commencing 1 day after tumor inoculation. Survival curves and median survival times (MST) are provided in FIG. 5A, which shows that PEGINTRON®, α2b-362, and α2b-413 all demonstratef significant improvement in survival when compared to saline control (P<0.0016), and the efficacy of α2b-362 or α2b-413 at the lowest dose (3,500 U) was similar or better than PEGINTRON® at the highest dose (14,000 IU). Both α2b-362 and α2b-413 at the two higher doses (7,000 and 14,000 U) were significantly superior to PEGINTRON® (P<0.0027). Moreover, α2b-413 was significantly more active than α2b-362 (P<0.0025) when administered at equivalent doses. Although the MST of mice treated with the 14,000 U dose was 60 days compared to 46 days of those treated with the 3,500 U dose, there were no statistically significant differences in survival benefit among the three doses of α2b-413 (P=0.1255). These in vivo efficacy results correlate well with the PK data and demonstrate that the two monopegylated dimers of IFN-α2b made by the DNL method are more potent and longer-lasting than PEGINTRON®, which prompted us to test whether less frequent dosing would be feasible with α2b-413.

We thus performed a second study in which PEGINTRON@ and α2b-413 at equal units of activity were administered with varied dosing schedules (FIG. 5B). All animals that received either form of IFN at any of the various schedules had significantly improved survival in comparison to saline control mice (P<0.0009). For bi-weekly (q2wk×4) therapy, mice treated with α2b-413 had significantly improved survival compared to those treated with PEGINTRON® (MST=66 days versus 28 days; P=0.0002). Importantly, mice treated every third week with α2b-413 (q3wk×4) not only had significantly improved survival in comparison to those treated with PEGINTRON® at the same schedule (MST=54 days versus 28 days; P=0.0002), they also showed longer MST than those treated with PEGINTRON® bi-weekly (MST=28 days; P=0.0002). However, when compared with mice treated with PEGINTRON® weekly (MST=36.5 days), the P value (0.3901) is statistically insignificant as only one mouse survived in this group.

In a third study (FIG. 5C), we found that administering α2b-413 at 14,000 IU every 4 weeks increased the median survival to 56 days from 23 days of the saline control and was more potent than PEGINTRON® given 14,000 IU every week.

Example 8 In Vitro and In Vivo Characterization of α2b-457

For a better comparison with PEGASYS®, we conjugated IFNα2b-DDD2 to IMP457, an AD2-module of 40-kDa branched PEG, and obtained a resulting α2b-457. Gel electrophoresis showed that α2b-457 was of substantial purity in a 0.5 M NaCl fraction eluted from a CM column (FIG. 6, lane 1, NR and R).

The iLite Human Interferon Alpha Cell-Based Assay Kit (PBL Interferon Source) was used to determine specific activities following the manufacturers' suggested protocol. Briefly, samples were diluted in 1% BSA-PBS to 5, 1.25 and 3.125 ng/mL for α2b-362 and α2b-413, to 10, 2.5 and 0.625 ng/mL for α2b-457 and PEGASYS®, and to 1, 0.25 and 0.0625 ng/mL for PEGINTRON®. Each dilution was assayed in triplicate and incubated overnight with the supplied cells. Specific activities were extrapolated from a standard curve generated with the supplied standard. The in vitro biological activities of α2b-457 were determined by three different assays (FIG. 7A-7C) to be lower than PEGINTRON®, comparable to α2b-413, and considerably higher than PEGASYS®. The PK data obtained in mice with a single s.c. injection are shown in FIG. 8, which indicate a longer circulating half-life of α2b-457 than either α2b-413 or PEGASYS®, with all three clearing much slower than PEGINTRON®.

Table 2 summarizes the key PK parameters calculated. The observed differences between α2b-457 and each of α2b-413, PEGASYS®, and PEGINTRON®, or between α2b-413 and PEGASYS® or PEGINTRON®, are significant by statistical analysis (Table 3). When given once every four weeks at a low dose of 20 pmol, α2b-457 was more effective than PEGINTRON® given as a mole-equivalent dose once weekly. Administration of α2b-457 extended the median survival of Daudi-bearing mice to 47 days from 23 days when compared to the saline group (FIG. 9). In the same study, α2b-457 at 20 pmol was significantly better than either α2b-413 or PEGINTRON® at 20 pmol (MST=47 days versus 41 and 37 days, respectively; P<0.0151). The 20 pmol dose of α2b-413 also improved survival in comparison to PEGINTRON® (P=0.002). At 10 pmol, there was no difference between α2b-457 and α2b-413 but both significantly improved survival over PEGINTRON® treated mice (P<0.001)

TABLE 2 Comparison of PK parameters. Injected Animal C_(max) T_(max) T_(1/2) AUC_(0→∞) Cl MRT_(0→∞) Material # (pmol/L) (h) (h) (h*pmole/L) (L/h) (h) α2b-457 1 4,326 24 16.9 169,119 0.0012 34.7 2 6,538 24 16.6 249,852 0.0008 33.4 3 5,424 24 16.3 192,651 0.0010 29.9 4 5,052 8 15.9 194,122 0.0010 31.6 5,335 ± 923 20 ± 8  16.4 ± 0.4 201,436 ± 34,250 0.0010 ± 0.0002 32.4 ± 2.1 α2b-413 1 3,014 24 15.5 123,440 0.0016 30.1 2 4,104 8 20.5 170,183 0.0012 30.1 3 2,888 24 11.3 92,415 0.0022 24.1 4 4,122 8 14.9 166,127 0.0012 27.0 3,532 ± 673 16 ± 9.2 15.6 ± 3.8 138,041 ± 37,044 0.0016 ± 0.0005 27.8 ± 2.9 PEGASYS ® 1 1,948 24 14.5 64,294 0.0016 33.1 2 1,887 24 14.6 58,596 0.0017 33.3 3 1,902 24 15.0 59,147 0.0017 34.1 4 2,377 24 15.3 47,116 0.0013 33.5 2,029 ± 234 24 14.9 ± 0.4 64,038 ± 7,192 0.0016 ± 0.0002 33.5 ± 0.4 PEGINTRON ® 1 1,885 8  9.4 34,063 0.0029 17.1 2 1,301 8  8.4 24,667 0.0041 15.5 3 1,609 8  9.8 32,833 0.0030 18.5 4 2,521 8  9.6 50,129 0.0020 17.3 1,829 ± 519 8  9.3 ± 0.6  35,423 ± 10,654 0.0030 ± 0.0008 17.1 ± 1.3

TABLE 3 Statistical analysis of PK parameters AUC P-value Cmax P-value α2b-457 vs. Fraction of Fraction of α2b-457 α2b-457 α2b-413 0.68 0.0457 0.66 0.0196 PEGASYS ® 0.32 0.0027 0.38 0.0041 PEGINTRON ® 0.18 0.0001 0.34 0.0006 α2b-413 vs. Fraction of Fraction of α2b-413 α2b-413 PEGASYS ® 0.46 0.0202 0.57 0.0056 PEGINTRON ® 0.26 0.0018 0.52 0.0071

In conclusion, we have PEGylated interferon-α2b (IFN-α2b) by the DNL method, which is capable of exclusively producing a class of monoPEGylated conjugates of IFN-α2b composed of two molecules of IFN-α2b and a single PEG chain. Three such monoPEGylated dimers of IFN-α2b retained anti-viral and anti-tumor activity in vitro and showed improved pharmacokinetic properties in vivo in mice, which translated into more potent and prolonged therapeutic efficacy in the Daudi human lymphoma model. This novel site-specific PEGylation technology provided extended circulation half-life and increased potency.

Example 9 Generation of DDD Module Based on Granulocyte-Colony Stimulating Factor (G-CSF)

Construction of G-CSF-DDD2-pdHL2 for Expression in Mammalian Cells

The cDNA sequence for G-CSF was amplified by PCR, resulting in a protein comprising G-CSF fused at its C-terminus to a polypeptide consisting of SEQ ID NO:23. PCR amplification was accomplished using a full-length human G-CSF cDNA clone (Invitrogen IMAGE human cat#97002RG Clone ID 5759022) as a template and the following oligonucleotides as primers:

G-CSF XbaI Left (SEQ ID NO: 26) 5′-TCTAGACACAGGACCTCATCATGGCTGGACCTGCCACCCAG-3′ G-CSF BamHI-Right (SEQ ID NO: 27) 5′-GGATCCATGATGGTGATGATGGTGTGACTTGGGCTGGGCAAGGTGG CGTAG-3′

The PCR amplimer was cloned into the pGemT vector. A DDD2-pdHL2 mammalian expression vector was prepared for ligation with G-CSF by digestion with XbaI and Bam HI restriction endonucleases. The G-CSF amplimer was excised from pGemT with XbaI and Bam HI and ligated into the DDD2-pdHL2 vector to generate the expression vector G-CSF-DDD2-pdHL2.

Mammalian Expression of G-CSF-DDD2

G-CSF-pdHL2 was linearized by digestion with SalI enzyme and stably transfected into Sp/EEE myeloma cells by electroporation. Clones were selected with media containing 0.15 MTX. Clone #4 was shown to produce 0.15 mg/L of G-CSF-DDD2 by sandwich ELISA.

Purification of G-CSF-DDD2 from Batch Cultures Grown in Roller Bottles

Approximately 3 mg of G-CSF-DDD2 is purified as descried in Example 2. A selected clone is expanded to 34 roller bottles containing a total of 20 L of Hybridoma SFM with 0.4 μM MTX and allowed to reach terminal culture. The supernatant fluid is clarified by centrifugation, filtered (0.2 μM), diafiltered into 1× Binding buffer (10 mM imidazole, 0.5 M NaCl, 50 mM NaH₂PO₄, pH 7.5) and concentrated. The concentrate is loaded onto a Ni-NTA column, which is washed with 0.02% Tween 20 in 1× binding buffer and then 30 mM imidazole, 0.02% Tween 20, 0.5 M NaCl, 50 mM NaH₂PO₄, pH 7.5. The product is eluted with 250 mM imidazole, 0.02% Tween 20, 150 mM NaCl, 50 mM NaH₂PO₄, pH 7.5.

Example 10 Generation of PEGylated G-CSF by DNL

A DNL complex is generated having the structure of two copies of G-CSF coupled to a 30 kDa PEG. The DNL reaction is performed by the addition of reduced and lyophilized IMP413 in 10-fold molar excess to G-CSF-DDD2 in PBS. After 6 h at room temperature in the dark, the reaction mixture is purified by immobilized metal affinity chromatography using Ni-NTA.

Example 11 Generation of DDD Module Based on Erythropoietin (EPO)

Construction of G-CSF-DDD2-pdHL2 for Expression in Mammalian Cells

The cDNA sequence for EPO was amplified by PCR resulting in sequences comprising EPO fused at its C-terminus to a polypeptide consisting of SEQ ID NO:23. PCR amplification was accomplished using a full-length human EPO cDNA clone as a template and the following oligonucleotides as primers:

EPO Xba I left (SEQ ID NO: 28) 5′-TCTAGACACAGGACCTCATCATGGGGGTGCACGAATGTCC-3′ EPO BamHI Right (SEQ ID NO: 29) 5′-GGATCCATGATGGTGATGATGGTGTGACTTTCTGTCCCCTGTCCTG CAG-3′

The PCR amplimer was cloned into the pGemT vector. A DDD2-pdHL2 mammalian expression vector was prepared for ligation with EPO by digestion with XbaI and Bam HI restriction endonucleases. The EPO amplimer was excised from pGemT with XbaI and Bam HI and ligated into the DDD2-pdHL2 vector to generate the expression vector EPO-DDD2-pdHL2.

Mammalian Expression of EPO-DDD2

EPO-pdHL2 was linearized by digestion with Sail enzyme and stably transfected into Sp/EEE myeloma cells by electroporation. Clones were selected with media containing 0.15 μM MTX. Clones #41, 49 and 37 each were shown to produce ˜0.5 mg/L of EPO by an ELISA using Nunc Immobilizer Nickel-Chelate plates to capture the His-tagged fusion protein and detection with anti-EPO antibody.

Purification of EPO from Batch Cultures Grown in Roller Bottles

Approximately 2.5 mg of EPO-DDD2 is purified by IMAC from 9.6 liters of serum-free roller bottle culture as described in Example 2. SDS-PAGE and immunoblot analysis indicate that the purified product constitutes approximately 10% of the total protein following IMAC (not shown). Under reducing conditions the EPO-DDD2 polypeptide is resolved as a broad band with a M_(r) (40-45 kDa) greater than its calculated mass (28 kDa) due to extensive and heterogeneous glycosylation. Under non-reducing conditions the EPO-DDD2 primarily resolves as a disulfide-linked covalent dimer (mediated by DDD2) with a M_(r) of 80-90 kDa.

Example 12 DNL Conjugation of EPO-DDD2 with a Fab-AD2 Module

h679 is a humanized monoclonal antibody that is highly specific for the hapten HSG (histamine-succinyl-glycine). Production of an h679-Fab-AD2 module has been described previously (Rossi et. al, Proc. Natl. Acad. Sci. USA. 2006; 103:6841). A small-scale preparation of EPO-679 (EPO-DDD2×h679-Fab-AD2) was made by DNL. EPO-DDD2 (1 mg) was reacted overnight with h679-Fab-AD2 (1 mg) in PBS containing 1 mM reduced glutathione and 2 mM oxidized glutathione. The DNL conjugate was purified by HSG-based affinity chromatography as described previously (Rossi et. al, Proc. Natl. Acad. Sci. USA. 2006; 103:6841). The structure of EPO-679 comprised two EPO moieties and h679-Fab. Coomassie blue staining of SDS-PAGE gels demonstrated the creation of EPO-679 (not shown). The DNL product, which is resolved as a broad band with a M_(r) of 150-170 kDa under non-reducing conditions, is highly purified and consists only of the three constituent polypeptides (EPO, h679-Fd-AD2 and h679 Kappa) as demonstrated by SDS-PAGE under reducing conditions (not shown).

Example 13 Biological Activity of EPO-DDD2 and EPO-679

EPO-DDD2 and EPO-679 were assayed for their ability to stimulate the growth of EPO-responsive TF1 cells (ATCC) using recombinant human EPO (Calbiochem) as a positive control. TF1 cells were grown in RPMI 1640 media supplemented with 20% FBS without GM-CSF supplementation in 96-well plates containing 1×10⁴ cells/well. The concentrations (units/ml) of the EPO constructs were determined using a commercial kit (Human erythropoietin ELISA kit, Stem Cell Research, Cat#01630). Cells were cultured in the presence of rhEPO, EPO-DDD2 or EPO-679 at concentrations ranging from 900 U/ml to 0.001 U/ml for 72 hours. The viable cell densities were compared by MTS assay using 20 μl of MTS reagent/well incubated for 6 hours before measuring the OD490 in a 96-well plate reader. Dose response curves and EC50 values were generated using Graph Pad Prism software (not shown). Both EPO-DDD2 and EPO-679 show in vitro biological activity at approximately 10% of the potency of rhEPO.

Example 14 Generation of PEGylated EPO by DNL

The structure of EPO-413 having two copies of EPO coupled to a 30 kDa PEG is made. A DNL reaction is performed by the addition of reduced and lyophilized IMP413 in 10-fold molar excess to EPO-DDD2 in PBS. After 6 h at room temperature in the dark, the reaction mixture is purified by immobilized metal affinity chromatography using Ni-NTA.

Example 15 Production of 2-PEG:1-Target Agent Complexes

In alternative embodiments, it may be desirable to make PEGylated complexes with a stoichiometry of 2 PEG moieties to 1 target agent. Such PEGylated complexes are readily made by the methods of Examples 1-3 above, by attaching the PEG moiety to the DDD sequence and the active agent to the AD sequence. A PEGylated complex with a 2:1 stoichiometry of PEG to IFN-α2b is prepared by a modification of the methods of Examples 1-3. The complex exhibits stability in serum and shows interferon activity that is lower than the PEGylated complex with a 1:2 stoichiometry of PEG to IFN-α2b. However, clearance rate for the bi-PEGylated complex is slower than the clearance rate for the mono-PEGylated complex. 

What is claimed is:
 1. A fusion protein comprising a) an interferon; and b) a dimerization and docking domain (DDD) moiety from human protein kinase A (PKA) regulatory subunit RIα, RIβ, RIIα or RIIβ.
 2. The fusion protein of claim 1, wherein the interferon is selected from the group consisting of interferon-alpha (IFN-α), IFN-β, IFN-γ and IFN-λ.
 3. The fusion protein of claim 1, wherein the interferon is IFN-α.
 4. The fusion protein of claim 1, wherein the interferon is IFN-β.
 5. The fusion protein of claim 1, wherein the interferon is IFN-γ.
 6. The fusion protein of claim 1, wherein the interferon is IFN-λ.
 7. A dimer comprising two copies of a fusion protein according to claim 1, wherein the two DDD moieties bind together to form the dimer.
 8. A fusion protein comprising a) an interferon; and b) an anchoring domain (AD) moiety from an A-kinase anchoring protein (AKAP).
 9. The fusion protein of claim 8, wherein the interferon is selected from the group consisting of IFN-α, IFN-β, IFN-γ and IFN-λ.
 10. The fusion protein of claim 8, wherein the interferon is IFN-α.
 11. The fusion protein of claim 8, wherein the interferon is IFN-β.
 12. The fusion protein of claim 8, wherein the interferon is IFN-γ.
 13. The fusion protein of claim 8, wherein the interferon is IFN-λ. 